U.S. patent application number 13/672432 was filed with the patent office on 2013-05-23 for metal complex compositions and methods for making metal-containing films.
The applicant listed for this patent is John R. ABELSON, Scott DALY, Gregory S. GIROLAMI, Do Young KIM, Navneet KUMAR, Yu YANG. Invention is credited to John R. ABELSON, Scott DALY, Gregory S. GIROLAMI, Do Young KIM, Navneet KUMAR, Yu YANG.
Application Number | 20130129593 13/672432 |
Document ID | / |
Family ID | 39864306 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130129593 |
Kind Code |
A1 |
GIROLAMI; Gregory S. ; et
al. |
May 23, 2013 |
Metal Complex Compositions and Methods for Making Metal-Containing
Films
Abstract
The present invention provides compositions of matter useful as
deposition agents for making structures, including thin film
structures and hard coatings, on substrates and features of
substrates. In an embodiment, for example, the present invention
provides metal complexes having one or more diboranamide or
diboranaphosphide ligands that are useful as chemical vapor
deposition (CVD) and/or atomic layer deposition (ALD) precusors for
making thin film structures and coatings. Metal complex CVD
precursors are provided that possess volitilities sufficiently high
so as to provide dense, smooth and homogenous thin films and
coatings.
Inventors: |
GIROLAMI; Gregory S.;
(Urbana, IL) ; KIM; Do Young; (Urbana, IL)
; ABELSON; John R.; (Urbana, IL) ; KUMAR;
Navneet; (Urbana, IL) ; YANG; Yu; (Urbana,
IL) ; DALY; Scott; (Urbana, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GIROLAMI; Gregory S.
KIM; Do Young
ABELSON; John R.
KUMAR; Navneet
YANG; Yu
DALY; Scott |
Urbana
Urbana
Urbana
Urbana
Urbana
Urbana |
IL
IL
IL
IL
IL
IL |
US
US
US
US
US
US |
|
|
Family ID: |
39864306 |
Appl. No.: |
13/672432 |
Filed: |
November 8, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12595384 |
Mar 11, 2010 |
8362220 |
|
|
PCT/US08/59728 |
Apr 9, 2008 |
|
|
|
13672432 |
|
|
|
|
60911619 |
Apr 13, 2007 |
|
|
|
60914948 |
Apr 30, 2007 |
|
|
|
Current U.S.
Class: |
423/286 ; 534/15;
549/213; 556/8; 564/10 |
Current CPC
Class: |
C07F 19/005 20130101;
C23C 16/40 20130101; H01B 1/12 20130101; C07F 5/022 20130101; H01B
1/06 20130101 |
Class at
Publication: |
423/286 ; 564/10;
549/213; 556/8; 534/15 |
International
Class: |
H01B 1/12 20060101
H01B001/12; C07F 19/00 20060101 C07F019/00; H01B 1/06 20060101
H01B001/06 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This invention was made with United States government
support awarded by the following agencies: NSF DMR03-15428. The
United States has certain rights in this invention.
Claims
1-55. (canceled)
56. A composition of matter comprising a metal complex having the
formula: M(B.sub.3H.sub.8).sub.xD.sub.y (F29) wherein M is a metal
atom selected from the group consisting of: Be, Mg, Ca, Sr, Ba, Ra,
Al, Ga, In, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Mn, Re, Fe,
Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Hg, Dy, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am,
and Cm; wherein each D, independent of other D, is a neutral
coordinating ligand; wherein x is the oxidation state of M; and
wherein y is 0, 1, 2, 3 or 4.
57. The composition of claim 56 wherein M is Mg and x is 2.
58. The composition of claim 56 wherein x is 1, 2, 3, or 4.
59. The composition of claim 56 wherein D is selected from the
group consisting of: alkenes (R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6),
alkynes (R.sup.3C.ident.CR.sup.4), ethers (R.sup.3OR.sup.4),
sulfides (R.sup.3SR.sup.4), amines (R.sup.3NR.sup.4R.sup.5),
nitriles (R.sup.3CN), isonitriles (R.sup.3NC), phosphines
(R.sup.3PR.sup.4R.sup.5), phosphites ((R.sup.30)P(OR.sup.4)
(OR.sup.5)), arsines (R.sup.3AsR.sup.4R.sup.5), and stibenes
(R.sup.3SbR.sup.4R.sup.5); wherein R.sup.3, R.sup.4, R.sup.5 and
R.sup.6 are functional groups independently selected from the group
consisting of hydrogen, alkyl, fluoroalkyl, aryl, alkenyl, alkynyl,
and trialkylsilyl.
60. The composition of claim 56 wherein D is selected from the
group consisting of: cyclic monoethers, linear polyethers, cyclic
polyethers, cyclic monoamines, linear polyamines, cyclic
polyamines, cyclic monophosphines, linear polyphosphines, cyclic
polyphosphines, cyclic monoalkenes, linear polyenes, linear dienes,
linear trienes, linear tetraenes, cyclic polyenes, cyclic dienes,
cyclic trienes, cyclic tetraenes, cyclic monoalkynes and cyclic
dialkynes.
61. The composition of claim 56 wherein D is selected from the
group consisting of tetrahydrofuran, 1,2-dimethoxyethane,
diethylether, and dimethyl ether.
62. The composition of claim 56 having a formula selected from the
group consisting of: Mg(B.sub.3H.sub.8).sub.2,
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, and
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2.
63-65. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to U.S.
provisional Patent Applications 60/911,619 filed Apr. 13, 2007 and
60/914,948 filed Apr. 30, 2007, which are hereby incorporated by
reference in their entirety.
BACKGROUND OF INVENTION
[0003] Metal diborides (MB.sub.2) possess outstanding properties
for thin film applications in microelectronics and hard coatings:
metal diborides such as TiB.sub.2, ZrB.sub.2 and HfB.sub.2 have
melting points often exceeding 3000.degree. C., electrical
resistivities as low as 15 .mu..OMEGA.-cm, and hardnesses
approaching 30 GPa. In addition, they are chemically robust. Some
metal borides are attractive as potential replacements for TiN as
electrically conductive diffusion barriers in integrated circuits,
preventing the interdiffusion of copper and silicon in
interconnects (See, S. Jayaraman et al. J. Vac. Sci. Technol., A
2005, 23, 1619-1625, J. W. Sung, J. Appl. Phys. 2002, 91,
3904-3911, U.S. Pat. Nos. 6,445,023 B1 and 6,872,639 B2). Moreover,
magnesium diboride (MgB.sub.2), which becomes superconducting below
ca. 40 K, is potentially useful for the fabrication of
superconductor-based integrated circuits. (See, M. Naito et al.
Supercond. Sci. Technol. 2004, 17, R1-R18, U.S. Pat. No.
6,797,341).
[0004] Physical vapor deposition (PVD) and chemical vapor
deposition (CVD) methods are primarily employed in preparing thin
films of metal diborides. In general, the PVD process deposits thin
films of the desired composition by generating highly reactive
particles from pure bulk targets by evaporation or sputtering
followed by transporting them onto the substrate on which the films
grow. In CVD, a molecular precursor that contains some or all of
the elements in the desired thin film, is vaporized and delivered
onto a hot substrate, sometimes in combination with other
precursors. Subsequent chemical reactions afford thin films of the
desired material on the substrate. CVD methods can produce uniform
coatings on high aspect-ratio trenches and holes, which is
difficult to accomplish by PVD methods, which tend to be "line of
sight" owing to its use of highly reactive particles.
[0005] Atomic layer deposition (ALD), which is a variant of the CVD
method, is based on self-limiting reactions. A substrate is exposed
to a precursor, which reacts to coat the substrate with a monolayer
(or less) of material. The excess precursor is then pumped away,
and the substrate is exposed to a second precursor, which reacts
with the thin layer generated by the first reactant. Then, the
excess of this second reactant is removed. By repeating this cycle,
or variants in which more than two precursors are employed, the
desired thin film can be grown layer by layer. One feature of ALD
is that it can provide highly conformal coatings in extremely
narrow, deep holes.
[0006] The PVD processes that have been performed for the
deposition of transition metal diboride thin films include
sputtering, co-sputtering, reactive sputtering, pulsed-laser
ablation and evaporation. Sputtering from MB.sub.2 targets is the
most frequently employed method for MB.sub.2 deposition among PVD
methods; thin films of TiB.sub.2, ZrB.sub.2, HfB.sub.2, VB.sub.2,
TaB.sub.2, and CrB.sub.2 have been deposited from each MB.sub.2
target..sup.1-5 TiB.sub.2 thin films have been prepared by a
co-sputtering method that uses separate Ti and B targets (See, J.
Pelleg et al. J. Appl. Phys. 2002, 91, 6099-6104; T. Shikama et al.
Thin Solid Films 1988, 156, 287-293). Reactive sputtering method
using B.sub.2H.sub.6 gas as a boron source has also been employed
to deposit TiB.sub.2 thin films. (See, H. O. Blom et al. J. Vac.
Sci. Technol., A 1989, 7, 162-165). In all these sputtering
methods, the fluxes of metal and boron must be precisely controlled
to produce stoichiometric MB.sub.2 deposits: different sputter
yields, different angular emission profiles, and different gas
scattering effects can cause there to be excess metal or excess
boron in the films. (See C. Mitterer, J. Solid State Chem., 133,
(1997) 279) Failure to produce stoichiometric MB.sub.2 films often
results in films with less useful properties. Although sputtering
itself can be performed at moderate substrate temperatures, high
temperature annealing processes are often necessary to obtain films
with desired properties. An alternative to sputtering, pulsed-laser
ablation, has been employed to produce TiB.sub.2 films (See, V.
Ferrando, et al. Thin Solid Films 2003, 444, 91-94). One
disadvantage of this PVD technique is that a high deposition
temperature of 720.degree. C. was necessary. Thin films of
TiB.sub.2 and ZrB.sub.2 have also been prepared by evaporation; the
films were, however, nonstoichiometric and required high deposition
temperatures of above 1000.degree. C. (See, R. F. Bunshah, Thin
Solid Films 1977, 40, 169-182). Although high-quality MB.sub.2
films have often been prepared by PVD methods, all these PVD
approaches have limited abilities to deposit uniform coatings onto
non-flat surfaces.
[0007] CVD methods for thin films of transition metal diborides can
be divided into two processes in terms of precursor types: 1)
processes using metal halide precursors and 2) processes using
single sources of metal hydroborate complexes. In the former, metal
halides are reduced in the presence of a boron source to metal
borides and hydrohalic acids (HX). TiB.sub.2 and ZrB.sub.2, for
example, have been prepared from the reaction of BCl.sub.3 and
H.sub.2 with TiCl.sub.4 and ZrCl.sub.4, respectively..sup.6,7
Diborane can be used in place of boron halides and H.sub.2: the
reaction between B.sub.2H.sub.6 and TiCl.sub.4 and TaCl.sub.5
produced TiB.sub.2 and TaB.sub.2 thin films, respectively..sup.8,9
However, CVD processes using halogen-based precursors require high
deposition temperatures of 600-1200.degree. C. and often leave
behind traces of halogen contaminants both of these features are
detrimental for many microelectronic applications. Another
disadvantage of this method is that few metal halides are volatile
below their decomposition temperatures.
[0008] Single source precursors to metal diborides have been
described that have the general stoichiometry MB.sub.xH.sub.y;
these bear tetrahydroborate (BH.sub.4.sup.-) or octahydrotriborate
(B.sub.3H.sub.8.sup.-) groups. The precursors Zr(BH.sub.4).sub.4,
Hf(BH.sub.4).sub.4, and Cr(B.sub.3H.sub.8).sub.2 have afforded the
corresponding MB.sub.2 thin films at temperatures as low as
150.degree. C..sup.10-12 The single source precursors are free of
heteroatoms such as halogens that could contaminate the films, and
the deposition temperatures are often lower than 400.degree. C.
[0009] For many metal boride phases, it is not possible to use
single source CVD precursors to grow films because no precursor of
stoichiometry MB.sub.xH.sub.y exists. Volatile M(BH.sub.4).sub.n
complexes of d-block transition metals are rare because the
BH.sub.4.sup.- ligand is sterically small and strongly reducing,
and in fact only Ti(BH.sub.4).sub.3, Zr(BH.sub.4).sub.4, and
Hf(BH.sub.4).sub.4 are known. Because BH4 is sterically small,
three or four BH.sub.4.sup.- ligands are required to saturate the
coordination sphere of a transition metal center and form a
volatile complex, which accordingly means a +3 or +4 oxidation
state for the metal center. Many transition metals, however, are
not stable in these oxidation states in the presence of strongly
reducing BH.sub.4.sup.- groups. By employing the sterically more
demanding hydroborate ligand, B.sub.3H.sub.8.sup.-, the highly
volatile chromium(II) complex of Cr(B.sub.3H.sub.8).sub.2 has been
prepared and have demonstrated its excellence as single source
precursor to very high quality CrB.sub.2 thin films..sup.12,13
However, although the B.sub.3H.sub.8.sup.- group is sterically
larger than the BH.sub.4.sup.- ligand, so far only chromium has
been shown to form a highly volatile transition metal species
suitable as a CVD precursor.
[0010] The lattice structure of MgB.sub.2 is identical with that of
the transition metal diborides, but the deposition of MgB.sub.2
thin films is complicated by one major challenge: loss of Mg from
the MgB.sub.2 phase at growth temperatures above ca. 400.degree.
C..sup.14 If enough Mg is lost, the MgB.sub.2 films become
non-superconducting. Several reports of the deposition of MgB.sub.2
by PVD methods have appeared. Kang and co-workers have produced
MgB.sub.2 films by depositing amorphous boron followed by reaction
with Mg vapor at 900.degree. C. in sealed tantalum tube..sup.15
Although this method has produced high-quality MgB.sub.2 films with
a critical temperature T.sub.c of 39 K, the ex-situ high
temperature annealing process must be conducted in a sealed tube,
which makes this method impractical for producing multilayer thin
films on a large scale. Ueda et al. have produced MgB.sub.2 thin
films with a T.sub.c of ca. 38 K by co-evaporation at 240 to
270.degree. C..sup.16,17 Zeng et al. have grown MgB.sub.2 thin
films by an in situ hybrid physical-chemical vapor deposition
(HP-CVD) method in which B.sub.2H.sub.6 reacts with Mg vapor
generated from Mg chips placed near the substrate..sup.18,19 The
main obstacle to employing this latter approach in the fabrication
of multilayer devices is the high deposition temperature of ca.
750.degree. C., which will promote undesirable interfacial
reactions.
[0011] A desirable method for incorporating MgB.sub.2 into
multilayer devices should produce crystalline, conformal films
below 400.degree. C. via an in situ deposition process without the
need for a subsequent annealing process at an elevated temperature.
To date, only the co-evaporation method comes close to this
requirement, but this method cannot afford conformal films on
topologically complex substrates. Thus, a need exists for designing
and synthesizing volatile magnesium-containing compounds for the
CVD of MgB.sub.2.
SUMMARY OF THE INVENTION
[0012] The present invention provides compositions of matter useful
as deposition agents for making structures, including thin film
structures and hard coatings, on substrates and features of
substrates. In an embodiment, for example, the present invention
provides metal complexes, including but not limited to transition
metal complexes and alkaline earth metal complexes (e.g., magnesium
complexes), having one or more diboranamide or diboranaphosphide
ligands that are useful as chemical vapor deposition (CVD), atomic
layer deposition (ALD) precusors, and/or molecular beam epitaxy
(MBE) precursors for making thin film structures and coatings.
Metal complex CVD, ALD and MBE precursors are provided that possess
volitilities sufficiently high so as to provide dense, smooth and
homogenous thin films and coatings. In addition, metal complexes of
the present invention useful as CVD, ALD and MBE precursors are
capable of accessing a range of useful thin film and coating
compositions, including metal oxide and metal boride thin films,
such as metal diboride films. In an embodiment, metal complexes of
the present invention provide single source CVD precursors for
making high purity metal diboride thin films and/or CVD precursors
capable of generating high purity thin films and/or coatings on
substrates at relative low substrate processing temperatures (e.g.,
less than about 450 degrees Celsius). The present invention also
provides methods of making metal complexes, including but not
limited to transition metal complexes and alkaline earth metal
complexes (e.g., magnesium complexes), having one or more
diboranamide or diboranaphosphide ligands useful as deposition
agents. As used herein and throughout this description, the term
"metal" includes transition metal elements including the d-block
transition metals and f-block metals, including both the
lanthanides and the actinides, and also includes metals other than
transition and f-block metals, including but not limited to,
alkaline earth metals such as magnesium, calcium, strontium and
barium.
[0013] The present invention provides CVD, ALD and MBE methods and
precursor compositions for making thin films exhibiting mechanical
and electronic properties useful for a range of electronic device
fabrication applications, including applications for making
integrated electronic devices and/or thin film electronic devices.
For example, the present CVD, ALD and MBE methods and precursor
compositions are capable of generating conformal and super
conformal thin films, layers and coatings on a range of substrates,
including electronic device substrates and substrates having
contoured surfaces. Metal complex compositions and CVD methods of
the present invention are capable of generating metal boride films
and coatings exhibiting a high melting point, good mechanical
hardness and large thermal and electrical conductivities. In
addition, the present CVD, ALD and MBE methods and precursor
compositions are useful for fabricating superconducting structures
comprising high purity metal diboride thin films. The present
methods are compatible with a wide range of existing materials
processing techniques and processing conditions, and are useful for
making a wide range of functional devices including, but not
limited to, integrated electronic circuits, macroelectronic device
arrays, memory devices, sensors, MEMS & NEMS systems,
photovoltaic devices, and micro- and nanofluidic systems.
[0014] In an aspect, the present invention provides metal complexes
having one or more diboranamide or diboranaphosphide ligands, which
are particularly useful for making metal-containing structures via
deposition techniques, such as CVD, ALD and MBE techniques. In an
embodiment, the invention provides a composition of matter
comprising a metal complex having the formula:
(ML.sub.x).sub.zD.sub.y (F1)
wherein each M, independent of other M, is a metal atom selected
from the group consisting of: Be, Mg, Ca, Sr, Ba, Ra, Al, Ga, In,
Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os,
Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Hg, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, and Cm.
wherein each D, independent of other D, is a neutral coordinating
ligand; wherein x is equal to the oxidation state of M; wherein y
is 0, 1, 2, 3 or 4; wherein z is 1, 2 or 3; wherein each L,
independent of other L, is an anionic ligand, wherein at least one
of L is a monoanionic group comprising a diboranamide or
diboranaphosphide group having the formula;
##STR00001##
wherein: each X is independently N or P; wherein, independently for
each L, R.sup.1 and R.sup.2 are functional groups independently
selected from the group consisting of hydrogen, alkyl, haloalkyl,
aryl, heteroaryl, trialkylsilyl, alkenyl, alkynyl, halogen,
fluoroalkyl, silylalkyl, alkoxy, hydroxyl, amide, boryl, and
thiolate. Optionally, in an embodiment L is has the formula
(F3);
##STR00002##
wherein m is an integer from 1 to 7. Optionally, in an embodiment
R.sup.1 and R.sup.2 are alkyl groups, such as C.sub.1 to C.sub.10
alkyl groups. Optionally, in an embodiment R.sup.1 and R.sup.2 are
methyl groups.
[0015] In an embodiment of this aspect of the present invention,
the metal complex comprises a monovalent metal, x is 1 and z is 1.
In these embodiments, (ML.sub.x).sub.z in formula F1 has the
formula ML. Monovalent metals useful in compositions of this
embodiment of the present invention include, but are not limited
to, Cu, Ag, and Au. In an embodiment, the present invention
provides a composition having the formula F1 wherein ML has a
formula selected from the group consisting of:
M((BH.sub.3).sub.2NR.sub.1R.sub.2) and
M((BH.sub.3).sub.2PR.sub.1R.sub.2). In an embodiment, for example,
ML has a formula selected from the group consisting of:
##STR00003##
Compositions of this embodiment of the present invention include,
but are not limited to, metal complexes having a formula selected
from the group consisting of:
##STR00004##
[0016] In another embodiment of this aspect of the present
invention, the metal complex comprises a divalent metal, x is equal
to 2 and z is equal to 1. In these embodiments, (ML.sub.x).sub.z in
formula F1 has the formula ML.sub.2. Divalent metals useful in
compositions of this embodiment of the present invention include,
but are not limited to, Be, Mg, Ca, Sr, Ba, Ra, Ti, V, Nb, Cr, Mo,
Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt. In an embodiment,
the present invention provides a composition having the formula F1
wherein ML.sub.2 has a formula selected from the group consisting
of: M((BH.sub.3).sub.2NR.sub.1R.sub.2).sub.2 and
M((BH.sub.3).sub.2PR.sub.1R.sub.2).sub.2. In an embodiment, for
example, ML.sub.2 has a formula selected from the group consisting
of:
##STR00005##
Compositions of this embodiment of the present invention include,
but are not limited to, metal complexes having a formula selected
from the group consisting of:
##STR00006##
[0017] In another embodiment of this aspect of the present
invention, the metal complex comprises one or more trivalent
metals, x is equal to 3 and z is equal to 1 or 2. In these
embodiments, (ML.sub.x).sub.z in formula F1 has the formula
(ML.sub.3).sub.z, wherein z is 1 or 2. Trivalent metals useful in
compositions of this embodiment of the present invention include,
but are not limited to, Al, Ga, In, Sc, Y, La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, and U. In an embodiment,
the present invention provides a composition having the formula F1
wherein (ML.sub.x).sub.z has a formula selected from the group
consisting of: M((BH.sub.3).sub.2NR.sub.1R.sub.2).sub.3,
M((BH.sub.3).sub.2PR.sub.1R.sub.2).sub.3,
(M((BH.sub.3).sub.2NR.sub.1R.sub.2).sub.3).sub.2 and
(M((BH.sub.3).sub.2PR.sub.1R.sub.2).sub.3).sub.2. In an embodiment,
for example, (ML.sub.x).sub.z has the formula ML.sub.3 and is
selected from the group consisting of:
##STR00007##
In another embodiment, for example, (ML.sub.x).sub.z has the
formula (ML.sub.3).sub.2 and has a dimeric structure selected from
the group consisting of:
##STR00008##
Compositions of this embodiment of the present invention include,
but are not limited to, metal complexes having a formula selected
from the group consisting of:
##STR00009## ##STR00010##
[0018] Compositions of the present invention also include complexes
similar to those illustrated by formula F18-F27 but containing
bridging diboranamide or diboranaphosphide ligands with the
BH.sub.3 groups coordinating to their respective metals in a
bidentate fashion via two B-H-M bridges. An example of this
embodiment is observed in Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6
and Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0019] Compositions of embodiment F18-F27 also include complexes
that contain bridging diboranamide or diboranaphosphide ligands
with the BH.sub.3 groups coordinating to their respective metals in
a tridentate fashion via three B-H-M bridges. An example of this
embodiment is observed in structural isomer B of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3.
[0020] Compositions of embodiment F18-F27 also include, but are not
limited to, complexes where the bridging diboranamide or
diboranaphosphide ligands are chelating one metal center while
simultaneously bridging to the adjacent metal center via a terminal
B-H-M bridge. Examples of this embodiment are observed in
Eu.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(thf).sub.4 and in
structural isomer A of U(H.sub.3BNMe.sub.2BH.sub.3).sub.3.
[0021] In an embodiment, the present invention provides
compositions wherein each L in formula F1 is a diboranamide or
diboranaphosphide group. Alternatively, the present invention
includes mixed ligand metal complexes wherein at least one L in
formula F1 is a diboranamide or diboranaphosphide group, but at
least one L in formula F1 is a different anionic group. In an
embodiment, for example, the present invention includes mixed
ligand metal complexes wherein at least one L in formula F1 is a
diboranamide or diboranaphosphide group, and at least one L in
formula F1 is an anionic ligand selected from the group consisting
of: a cyclopentadienyl, a borohydride, .beta.-diketonate,
octahydroborato group, indenyl, .beta.-diketiminate, pyrazolate,
triazolate, amidinate, alkyl, alkoxide, thiolate, amide, imide,
halide, hydride, sulfide, cyanide, thiocyanate, isothiocyanate,
hydroxide, oxide, oxalate, nitrides, nitrite, nitrate, azide,
phosphate, phosphite, and cyclooctatetraene dianion. In an
embodiment, for example, the present invention includes mixed
ligand metal complexes wherein at least one L in formula F1 is a
diboranamide or diboranaphosphide group, and at least one L in
formula F1 is an anionic ligand selected from the group consisting
of: cyclopentadienyl, monomethylcyclopentadienyl,
1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl,
1,2,3-trimethylcyclopentadienyl, 1,2,4-trimethylcyclopentadienyl,
tetramethylcyclopentadienyl, pentamethylcyclopentadienyl,
(trimethylsilyl)cyclopentadienyl, 1,3
bis(trimethylsilyl)cyclopentadienyl,
1,2,4-tris(trimethylsilyl)cyclopentadienyl,
trifluoromethylcyclopentadienyl, tetrahydroborate,
trihydrocyanoborate, trihydromethylborate; acetylacetonate
(2,4-pentanedione anion), 1,1,1-(trifluoro)acetylacetonate
(1,1,1-trifluoro-2,4-pentanedione anion), hexafluoroacetylacetonate
(1,1,1,5,5,5-hexafluoro-2,4-pentanedione anion),
1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione anion,
2,2,4,4-tetramethyl-3,5-heptanedione anion, and octahydroborato
(B.sub.3H.sub.8.sup.-). As will be generally understood by those
having skill in the art, the description above provides specific
examples of anionic ligands for metal complexes of the present
invention. Compositions having ligands other than those
specifically exemplified are within the scope of the present
invention.
[0022] A wide range of neutral coordinating ligands (D) are useful
in the present compositions. In an embodiment, for example, D is a
two-electron donor ligand. In an embodiment, neutral coordinating
ligands (D) for the present compositions are selected from the
group consisting of: alkenes (R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6),
alkynes (R.sup.3CCR.sup.4), ethers (R.sup.3OR.sup.4), sulfides
(R.sup.3SR.sup.4), amines (R.sup.3NR.sup.4R.sup.5), nitriles
(R.sup.3CN), isonitriles (R.sup.3NC), phosphines
(R.sup.3PR.sup.4R.sup.5), phosphites ((R.sup.30)P(OR.sup.4)
(OR.sup.5)), arsines (R.sup.3AsR.sup.4R.sup.5), and stibenes
(R.sup.3SbR.sup.4R.sup.5); wherein R.sup.3, R.sup.4, R.sup.5 and
R.sup.6 are functional groups independently selected from the group
consisting of hydrogen, alkyl, fluoroalkyl, aryl, alkenyl, alkynyl,
and trialkylsilyl. In an embodiment, neutral coordinating ligands
(D) for the present compositions are selected from the group
consisting of: cyclic monoethers, linear polyethers, cyclic
polyethers, cyclic monoamines, linear polyamines, cyclic
polyamines, cyclic monophosphines, linear polyphosphines, cyclic
polyphosphines, cyclic monoalkenes, linear polyenes, linear dienes,
linear trienes, linear tetraenes, cyclic polyenes, cyclic dienes,
cyclic trienes, cyclic tetraenes, cyclic monoalkynes, cyclic
dialkynes, carbonyls, and trifluorophosphines.
[0023] In an embodiment, coordinating ligands (D) for the present
compositions are selected from the group consisting of:
tetrahydrofuran, 1,2-dimethoxyethane, diethylether, and dimethyl
ether.
[0024] Composition of the present invention particularly attractive
for use as a CVD, ALD or MBE precursor include, but are not limited
to, Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2;
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(tetrahydrofuran);
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dimethoxyethane);
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2;
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2;
Mo(H.sub.3BNMe.sub.2BH.sub.3).sub.2;
Mn(H.sub.3BNMe.sub.2BH.sub.3).sub.2;
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6;
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
La.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6;
La(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Ce.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6;
Ce(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Pr(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Nd(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Eu(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6;
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran);
Er.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6;
Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran), and
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(tetrahydrofuran).
[0025] In another aspect, the present invention provides methods of
making structures via deposition techniques, including chemical
vapor deposition, atomic layer deposition, high density plasma
(HDP) CVD, hot filament (surface) chemical vapor deposition and/or
molecular beam epitaxy (MBE) techniques. In an embodiment of this
aspect, the invention provides a method of making a structure
comprising the step of contacting a substrate or a feature of a
substrate with one or more metal complexes of the present invention
having one or more diboranamide or diboranaphosphide ligands.
Methods of this aspect of the present invention may further
comprise the step of decomposing the metal complex(es) on a surface
of the substrate or a surface of the feature of the substrate.
Methods of the present invention are capable of generating
structures having a wide range of shapes and physical dimensions,
including physical dimensions ranging from a few nanometers to
1000s of microns, that comprise device components of an electronic
device. Methods of the present invention are capable of generating
structures on substrate features comprising prepatterned device
components, on relief features of the substrate and recessed
features of the substrate, such as a trench, trough, slit, channel,
and via.
[0026] Metal complexes useful in this aspect of the invention are
described above and exemplified in detail throughout the present
description. Use of metal complexes having a high volatility is
particularly beneficial for generating dense films and coatings
having a substantially homogenous composition. Methods of this
aspect of the present invention are capable of generating
structures comprising metal-containing structures such as metal
oxide and/or metal boride films, layers and coatings. In a
preferred embodiment, deposition methods of the present invention
generate metal diboride films exhibiting useful mechanical, thermal
and electronic properties. Methods of this aspect of the present
invention are also capable of generating structures comprising
conformal or super-conformal films, layer and coatings on a range
of substrates including electronic device substrates that are
prepatterned with device components. Methods of this aspect of the
present invention are also capable of generating structures
comprising superconducting materials, such as MgB.sub.2 films,
useful in high performance electronic devices. Methods of this
aspect of the present invention are also capable of generating hard
coatings useful in a range of applications.
[0027] A method of making a structure of the present invention
further comprises the steps of vaporizing one or more metal
complexes of the present invention having one or more diboranamide
or diboranaphosphide ligands, thereby generating a deposition gas,
and contacting the substrate or the feature of a substrate with the
deposition gas. In an embodiment, this processing step generates a
deposition gas which is a chemical vapor deposition precursor, a
MBE precursor or an atomic layer deposition precursor. Methods of
this embodiment may optionally comprise the step of heating the
substrate or the feature of the substrate during the step of
contacting the substrate or the feature of a substrate with the
deposition gas. Use of some metal complexes of the present
invention having one or more diboranamide or diboranaphosphide
ligands enables CVD, ALD and/or MBE methods wherein the substrate
or the feature of the substrate is heated to a temperature less
than or equal to approximately 450 degrees Celsius during
processing. Such lower temperature deposition methods of the
present invention are useful for accessing a broad range of thin
film and coating compositions, including boron containing films and
coatings, having useful mechanical and electronic properties.
[0028] In some embodiments, the present deposition methods utilize
a metal complex having one or more diboranamide or
diboranaphosphide ligands that comprises a single source CVD, ALD
or MBE precursor. In these methods, metal-containing structures are
generated by exposure of the substrate and/or feature of the
substrate to a single CVD, ALD and/or MBE precursor of the present
invention. Alternatively, the present invention includes deposition
methods using one or more additional deposition gases or additives.
In an embodiment, for example, the present methods further comprise
the steps of providing one or more additional deposition gases; and
contacting the substrate or the feature of the substrate with the
one or more additional deposition gases. Additional depositions
gases useful in the present invention include CVD, ALD and/or MBE
precursors, including but not limited to, metal complexes of the
present invention having one or more diboranamide or
diboranaphosphide ligands.
[0029] The present invention includes deposition methods wherein
the substrate and/or deposition gas are contacted with an additive
during processing. In an embodiment, for example, the methods of
the present invention further comprise the step of contacting the
substrate or feature thereon with one or more chemical vapor
deposition catalysts during deposition processing. Such embodiments
of the present invention include catalyst assisted deposition
methods that are particularly useful for accessing a broad range of
thin film or coating compositions, including doped thin
film/coating compositions. In another embodiment, deposition
methods of the present invention further comprise the step of
providing one or more deposition additives in contact with the
deposition gas during the step of contacting the substrate or the
feature of a substrate with the deposition gas. Use of additives in
this aspect of the present invention is beneficial for accessing a
range of useful thin film or coating compositions. Useful additives
for generating metal oxide, metal nitride, boronitrides or
borocarbo-nitrides thin film and/or coating compositions include,
but are not limited to, H.sub.2O, O.sub.2, O.sub.3, NO.sub.2,
NH.sub.3, N.sub.2H.sub.4, CO.sub.2, and H.sub.2.
[0030] In another aspect, the present invention provides methods of
making metal complexes having one or more diboranamide or
diboranaphosphide ligands. In an embodiment, for example, the
present invention provides a method of synthesizing a metal complex
comprising the steps of:
(i) providing a metal salt having a formula selected from the group
consisting of MCl.sub.n, MBr.sub.n, and MI.sub.D, wherein M, is a
metal selected from the group consisting of: Be, Mg, Ca, Sr, Ba,
Ra, Al, Ga, In, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn,
Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Hg, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np,
Pu, Am and Cm; wherein n is 1, 2, 3 or 4; and (ii) contacting the
metal salt with an alkali metal diboranamide reagent or alkali
metal diboranaphosphide reagent having the formula:
##STR00011##
wherein A is an alkali metal; wherein X is N or P; wherein R.sup.1
and R.sup.2 are functional groups independently selected from the
group consisting of hydrogen, alkyl, haloalkyl, aryl, heteroaryl,
trialkylsilyl, alkenyl, alkynyl, halogen, fluoroalkyl, silylalkyl,
alkoxy, hydroxyl, aldehyde, amide, nitrile, ether, ester, and
thiol.
[0031] In an embodiment of this aspect of the present invention
R.sup.1 and R.sup.2 are alkyl groups, such as C.sub.1 to C.sub.10
alkyl groups, for example methyl groups. In an embodiment, the
alkali metal diboranamide reagent or alkali metal diboranaphosphide
reagent is selected from the group consisting of:
Na(H.sub.3BNMe.sub.2BH.sub.3), K(H.sub.3BNMe.sub.2BH.sub.3),
Li(H.sub.3BNMe.sub.2BH.sub.3), Na(H.sub.3BPMe.sub.2BH.sub.3),
K(H.sub.3BPMe.sub.2BH.sub.3), Li(H.sub.3BPMe.sub.2BH.sub.3) and
adducts of these reagents with donor molecules such as, adducts of
these reagents with tetrahydrofuran, 1,2-dimethoxyethane,
diethylether, and dimethyl ether.
[0032] Synthetic methods for making metal complexes of the present
invention can be carried out in the solid phase or in the solution
phase. In an embodiment, for example, methods of the present
invention comprise the step of contacting the metal salt and the
alkali metal diboranamide reagent or alkali metal diboranaphosphide
reagent in the solid phase, for example via mixing solid reagents.
Alternatively, methods of the present invention in some embodiments
comprise the step of contacting the metal salt and the alkali metal
diboranamide reagent or alkali metal diboranaphosphide reagent in a
solvent. Solvents for the present synthetic methods may be selected
from the group consisting of ethers, polyethers, cyclic ethers,
thiothers, amines (aliphatic or aromatic, primary, secondary, or
tertiary), polyamines, nitriles, cyanates, isocyanates,
thiocyanates, esters, aldehydes, toulene, saturated or unsaturated
hydrocarbons (linear, branched, or cyclic), halogenated
hydrocarbons, silylated hydrocarbons, amides or compounds
containing combinations of any of the above, or mixtures of one or
more of the above. Useful solvents in synthetic methods of the
present invention include, but are not limited to, tetrahydrofuran,
dimethoxyethane, diethylether, and dimethyl ether.
[0033] Synthetic methods of the present invention may further
comprise one or more purification steps. As will be understood by
those having skill in the art a variety of purification methods may
be used in the present methods, including sublimation,
chromatographic methods, crystallization, vacuum removal of
solvent, washing, and solvent extraction. Purification via
sublimation is preferred for some applications of the present
invention.
[0034] In another aspect the present invention comprises a device
component or electronic device comprising one or more structures
generated by a method comprising the step of contacting a substrate
or a feature of a substrate with one or more metal complexes of the
present invention having one or more diboranamide or
diboranaphosphide ligands.
[0035] In another aspect, the present invention provides a
composition of matter comprising a metal complex having the
formula:
M(B.sub.3H.sub.8).sub.xD.sub.y (F29)
wherein M is a metal atom selected from the group consisting of:
Be, Mg, Ca, Sr, Ba, Ra, Al, Ga, In, Sc, Y, La, Ti, Zr, Hf, V, Nb,
Ta, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au,
Zn, Hg, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac,
Th, Pa, U, Np, Pu, Am, and Cm; wherein each D, independent of other
D, is a neutral coordinating ligand; wherein x is the oxidation
state of M; and wherein y is 0, 1, 2, 3 or 4. In an embodiment of
this aspect of the invention, M is optionally Mg.
[0036] Similar to the compositions described above in the context
of formula F1, D can optionally be a two-electron donor ligand. In
an embodiment, D is selected from the group consisting of: alkenes
(R.sup.3R.sup.4C.dbd.CR.sup.5R.sup.6), alkynes
(R.sup.3C.ident.CR.sup.4), ethers (R.sup.3OR.sup.4), sulfides
(R.sup.3SR.sup.4), amines (R.sup.3NR.sup.4R.sup.5), nitriles
(R.sup.3CN), isonitriles (R.sup.3NC), phosphines
(R.sup.3PR.sup.4R.sup.5), phosphites ((R.sup.30)P(OR.sup.4)
(OR.sup.5)), arsines (R.sup.3AsR.sup.4R.sup.5), and stibenes
(R.sup.3SbR.sup.4R.sup.5); wherein R.sup.3, R.sup.4, R.sup.5 and
R.sup.6 are functional groups independently selected from the group
consisting of hydrogen, alkyl, fluoroalkyl, aryl, alkenyl, alkynyl,
and trialkylsilyl. In an embodiment, D is selected from the group
consisting of: cyclic monoethers, linear polyethers, cyclic
polyethers, cyclic monoamines, linear polyamines, cyclic
polyamines, cyclic monophosphines, linear polyphosphines, cyclic
polyphosphines, cyclic monoalkenes, linear polyenes, linear dienes,
linear trienes, linear tetraenes, cyclic polyenes, cyclic dienes,
cyclic trienes, cyclic tetraenes, cyclic monoalkynes and cyclic
dialkynes. In an embodiment, D is selected from the group
consisting of tetrahydrofuran, 1,2-dimethoxyethane, diethylether,
and dimethyl ether.
[0037] In an embodiment, the composition of this aspect of the
invention has a formula selected from the group consisting of:
Mg(B.sub.3H.sub.8).sub.2,
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, and
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2.
[0038] Compositions of this aspect of the present invention (i.e.,
having the formula F29) are useful as deposition agents in a
variety of application including use as CVD ALD and MBE precursors.
Similar to the description of uses of the compositions formula F1,
compositions having the formula F29 are useful for making a wide
range of metal containing structures, including thin films, thin
film structures and coatings.
[0039] In another aspect, the present invention provides a method
of making a structure comprising the step of contacting a substrate
or a feature of a substrate with a composition having the formula
F29. Optionally, methods of this aspect may further comprise the
step of decomposing said composition having formula F29 on a
surface of said substrate or a surface of said feature of said
substrate. Optionally, methods of this aspect may further
comprising the steps of: vaporizing the composition having formula
F29, thereby generating a deposition gas; and contacting said
substrate or said feature of said substrate with said deposition
gas.
[0040] In an embodiment, a composition of the invention is isolated
or purified. In an embodiment, an isolated or purified compound may
be at least partially isolated or purified as would be understood
in the art.
[0041] Without wishing to be bound by any particular theory, there
can be discussion herein of beliefs or understandings of underlying
principles or mechanisms relating to the invention. It is
recognized that regardless of the ultimate correctness of any
explanation or hypothesis, an embodiment of the invention can
nonetheless be operative and useful.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1. The molecular structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, which was determined by single
crystal X-ray crystallography.
[0043] FIG. 2. Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, a monomeric
compound that contains two [H.sub.3BNMe.sub.2BH.sub.3].sup.-
ligands binding to the titanium center by means of eight Ti-H
contacts.
[0044] FIG. 3. Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, a dimeric
compound in which each yttrium center contains two
[H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands and two
[H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands bridge between two
yttrium centers.
[0045] FIG. 4. B-H stretching region in the infrared spectra of (a)
NaB.sub.3H.sub.8, (b) Mg(B.sub.3H.sub.8).sub.2, (c)
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, (d)
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2.
[0046] FIG. 5. .sup.1H NMR spectrum of
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, 2, in
(C.sub.2D.sub.5).sub.2O at 20.degree. C.
[0047] FIG. 6. Molecular structure of
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, 2. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0048] FIG. 7. Molecular structure of
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2, 3. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl hydrogen atoms
have been deleted for clarity.
[0049] FIG. 8. Molecular structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, 1. Ellipsoids are drawn at the
30% probability level, except for hydrogen atoms, which are
represented as arbitrarily sized spheres. Methyl hydrogen atoms
have been deleted for clarity.
[0050] FIG. 9. Molecular structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf), 2. Ellipsoids are drawn
at the 30% probability level, except for hydrogen atoms, which are
represented as arbitrarily sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0051] FIG. 10. Molecular structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme), 3. Ellipsoids are drawn
at the 30% probability level, except for hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0052] FIG. 11. Molecular structure of
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf), 4. Ellipsoids are drawn at
the 30% probability level, except for hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0053] FIG. 12. .sup.1H NMR spectrum of
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 1, in CD.sub.2Cl.sub.2 at
20.degree. C.
[0054] FIG. 13. a) Molecular structure of
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 1. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily sized spheres. Methyl hydrogen atoms
have been deleted for clarity. b) Top view of 1 showing the
unsymmetrical binding mode of the bridging diboranamide
ligands.
[0055] FIG. 14. Molecular structure of
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 2. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily sized spheres. Methyl hydrogen atoms
have been deleted for clarity.
[0056] FIG. 15. Molecular structure of
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 3. Molecule 1 is shown;
molecule 2 adopts essentially same structure. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0057] FIG. 16. Molecular structure of
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 4. Molecule 1 is shown;
molecule 2 adopts essentially same structure. Ellipsoids are drawn
at the 35% probability level, except for hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0058] FIG. 17. Auger depth profile of a
Mg.sub.0.8Ti.sub.0.2B.sub.2 film grown from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree.
C.
[0059] FIG. 18. RBS spectrum of a Mg.sub.0.8Ti.sub.0.2B.sub.2 film
grown from Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree. C.
The red line is the curve fit used to calculate the magnesium and
titanium contents.
[0060] FIG. 19. XPS survey spectrum of a
Mg.sub.0.8Ti.sub.0.2B.sub.2 film grown from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree. C.
after sputtering away the surface coat.
[0061] FIG. 20. XPS spectra in the Mg 2p (top), Ti 2p (middle), and
B 1s (bottom) regions of a Mg.sub.0.8Ti.sub.0.2B.sub.2 film grown
from Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree.
C.
[0062] FIG. 21. The XRD profiles of Mg.sub.1-xTi.sub.xB.sub.2 films
grown from Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at various
temperatures.
[0063] FIG. 22. Lattice constants a and c of the
Mg.sub.1-xTi.sub.xB.sub.2 films grown from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350 and
400.degree. C. The lattice constants are calculated from the XRD
profiles.
[0064] FIG. 23. Cross sectional SEM micrograph of a
Mg.sub.0.8Ti.sub.0.2B.sub.2 film grown from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree.
C.
[0065] FIG. 24. Cross sectional TEM image (top) and high resolution
TME image showing lattice fringes (bottom) of a
Mg.sub.0.8Ti.sub.0.2B.sub.2 film grown from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 on Si(100) at 350.degree.
C.
[0066] FIG. 25. Pressure rise of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 as a function of time in a
sealed container.
[0067] FIG. 26. Growth rates of MgO films as a function of
substrate temperatures. The Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
H.sub.2O pressures were kept at 2.times.10.sup.-5 Torr and
3.times.10.sup.-5 Torr, respectively.
[0068] FIG. 27. a) Growth rate variation as monitored by real-time
spectroscopic ellipsometry along a linear increase of substrate
temperature. The Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and H.sub.2O
pressures were kept at 2.times.10.sup.-5 Torr and 3.times.10.sup.-5
Torr, respectively. b) Growth rate as a function of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 pressure at 225.degree. C. and
a H.sub.2O pressure of 3 mTorr.
[0069] FIG. 28. SEM images of the conformal MgO films grown on
trenches. The trench shown in a) has a depth to width ratio of
30:1.
[0070] FIG. 29. AES depth profiling of the MgO films on silicon
substrate deposited at a) 275.degree. C. and b) 400.degree. C.
[0071] FIG. 30. RBS of a MgO film grown at 500.degree. C. on
silicon substrate. The noised and smooth lines are the measured and
fitted spectra, respectively.
[0072] FIG. 31. Cross sectional SEM images of the MgO films on
silicon substrates deposited at 275, 400, and 600.degree. C.
[0073] FIG. 32. XRD results of the MgO films deposited at various
temperatures on silicon substrates except for the top profile where
a glass substrate was used.
[0074] FIG. 33. a) Refractive index of the MgO films deposited at
275 and 600.degree. C. compare to that of the bulk MgO. b)
Transmittance spectra of the MgO films deposited at 275 and
600.degree. C.
[0075] FIG. 34. AES depth profiling of a Y.sub.2O.sub.3 and a
TiO.sub.2 film deposited on silicon substrates at 300.degree.
C.
[0076] FIG. 35. Cross sectional SEM images of the Y.sub.2O.sub.3
and TiO.sub.2 films deposited on silicon substrates by CVD.
[0077] FIG. 36. XRD profile of a Y.sub.2O.sub.3 film deposited on a
Si(100) substrate at 800.degree. C.
[0078] FIG. 37. AES depth profiling of a Y.sub.2O.sub.3 film
deposited on a silicon substrate at low H.sub.2O pressure.
[0079] FIG. 38. Molecular structure of
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4. Ellipsoids are drawn at the
35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres.
[0080] FIG. 39. Molecular structure of
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sub.2. Ellipsoids are
drawn at the 35% probability level, except for the hydrogen atoms,
which are represented as arbitrarily-sized spheres.
[0081] FIG. 40. Molecular structure of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3, structural isomer A. Ellipsoids
are drawn at the 35% probability level, except for the hydrogen
atoms, which are represented as arbitrarily-sized spheres. Methyl
and methylene hydrogen atoms have been deleted for clarity.
[0082] FIG. 41. Molecular structure of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3, structural isomer B. Ellipsoids
are drawn at the 35% probability level, except for the hydrogen
atoms, which are represented as arbitrarily-sized spheres.
[0083] FIG. 42. Molecular structure of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf). Ellipsoids are drawn at
the 35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0084] FIG. 43. Molecular structure of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(PMe.sub.3).sub.2. Ellipsoids are
drawn at the 35% probability level. Hydrogen atoms have been
deleted for clarity.
[0085] FIG. 44. Molecular structure of
La(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf). Ellipsoids are drawn at
the 35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0086] FIG. 45. Molecular structure of
Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf). Ellipsoids are drawn at
the 35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0087] FIG. 46. Molecular structure of
Eu(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf). Ellipsoids are drawn at
the 35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0088] FIG. 47. Molecular structure of
Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf). Ellipsoids are drawn at
the 35% probability level, except for the hydrogen atoms, which are
represented as arbitrarily-sized spheres. Methyl and methylene
hydrogen atoms have been deleted for clarity.
[0089] FIG. 48. Molecular structure of
Eu.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(thf).sub.4. Ellipsoids
are drawn at the 35% probability level. Hydrogen atoms have been
omitted for clarity.
[0090] Example 12, Table 1. Crystallographic Data for
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 (2),
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2 (3).
[0091] Example 12, Table 2. Selected Bond Lengths (A) and Angles
(deg) for Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 (2)..sup.a
[0092] Example 12, Table 3. Selected Bond Lengths (A) and Angles
(deg) for Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2 (3).
[0093] Example 13, Table 1. Crystallographic Data for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 (1),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf) (2),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme) (3), and
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf) (4).
[0094] Example 13, Table 2. Selected Bond Lengths (A) and Angles
(deg) for Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 (1)..sup.a Example
13, Table 3. Selected Bond Lengths (A) and Angles (deg) for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf) (2).
[0095] Example 13, Table 4. Selected Bond Lengths (A) and Angles
(deg) for Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme) (3).
[0096] Example 13, Table 5. Selected Bond Lengths (.ANG.) and
Angles (deg) for Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf) (4).
[0097] Example 14, Table 1. Crystallographic Data for
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 (1),
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) (2),
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 (3), and
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) (4).
[0098] Example 14, Table 2. Selected Bond Lengths (A) and Angles
(deg) for Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 (1).
[0099] Example 14, Table 3. Selected Bond Lengths (A) and Angles
(deg) for Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 (2).
[0100] Example 14, Table 4. Selected Bond Lengths (A) and Angles
(deg) for Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) (3).
[0101] Example 14, Table 5. Selected Bond Lengths (A) and Angles
(deg) for Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) (4).
[0102] Example 15, Table 1. Compositions of films obtained from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 in the presence of various
co-reactants. All films were deposited on Si(100) substrates at
350.degree. C. with a Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 line
pressure of .about.150 mTorr. The film stoichiometries were
determined from Auger depth profiles; films that deviate from the
MB.sub.2 stoichiometry may be compositionally heterogeneous.
[0103] Example 16, Table 1. Summary of the magnesium containing
precursors used for CVD/ALD growth of MgO thin films.
DETAILED DESCRIPTION OF THE INVENTION
[0104] Referring to the drawings, like numerals indicate like
elements and the same number appearing in more than one drawing
refers to the same element. In addition, hereinafter, the following
definitions apply:
[0105] The expression "metal complex" refers to a composition
comprising one or more metal atoms associated with one or more
other groups including ligand groups such as neutral coordinating
ligands and ionic coordinating ligands. Metal complexes include
coordination compounds comprising one or more metals bound to one
or more other groups via coordinate covalent bonds, ionic compounds
comprising one or more metals participating in ionic bonding with
one or more other groups, and compounds wherein one or more metals
are bonded to one or more other groups via covalent and/or ionic
bonding. Metal complexes of the present invention include metals
bound to one or more ligands selected from the group consisting of
diboranamide group ligands, diboranaphosphide group ligands, and
optionally anionic ligands other than diboranamide group ligands,
diboranaphosphide group ligands, and optionally neutral
coordinating ligands. In some embodiments, metal complexes of the
present invention include mixed ligand compositions including
metals bound to one or more anionic ligands including one or more
diboranamide group ligands and/or diboranaphosphide group ligands
and one or more anionic ligands other than diboranamide group
ligands and/or diboranaphosphide group ligands, and optionally
neutral coordinating ligands.
[0106] The expression "diboranamide group" refers to a group having
a charge of -1, in which two BH.sub.3 units and two organic
substituents are bound to a central nitrogen atom. The expression
"diboranaphosphide group" refers to a group having a charge of -1,
in which two BH.sub.3 units and two organic substituents are bound
to a central phosphorus atom. The diboranamide group and
diboranaphosphide group may be illustrate by the formula:
##STR00012##
wherein X is N for the diboranamide group and x is P for the
diboranaphosphide group. R.sup.1 and R.sup.2 may be a range of
functional groups including, but not limited to, hydrogen, alkyl,
haloalkyl, aryl, heteroaryl, trialkylsilyl, alkenyl, alkynyl,
halogen, fluoroalkyl, silylalkyl, alkoxy, hydroxyl, amide, boryl,
and thiolate. The H.sub.3BNMe.sub.2BH.sub.3 group may be referred
to by the abbreviation "DMDBA".
[0107] The expression "neutral coordinating ligand" refers to a
ligand that does not possess a net electrical charge. Neutral
coordinating ligands are not ionic species. Neutral coordinating
ligands include, but are not limited to, Lewis bases such as
two-electron donor ligands. Neutral coordinating ligands include
mondentate, bidentate and polydentate ligands.
[0108] Tetrahydrofuran may be referred to by the abbreviation
"thf".
[0109] Dimethoxyethane may be referred to by the abbreviation
"DME".
[0110] The expression "oxidation state of a metal" refers to an
indicator of the degree of oxidation of a metal atom in a chemical
compound. The oxidation state is the hypothetical charge that the
metal atom would have if all ligands are assigned closed shell
electronic structures. Metal atoms capable of having an oxidation
state of 1 include, but are not limited to, Li, Na, K, Rb, Cs, Cu,
Ag, Au, Hg, and TI. Metal atoms capable of having an oxidation
state of +2 include, but are not limited to, Be, Mg, Ca, Sr, Ba,
Ra, Ti, V, Nb, Cr, Mo, Mn, Re, Eu, Yb, Sm, Ru, Os, Co, Rh, Ir, Ni,
Pd, Pt, W, and Fe. Metal atoms capable of having an oxidation state
of +3 include, but are not limited to, Al, Ga, In, Sc, Y, La, Ti,
V, Nb, Ta, Cr, Mo, W, Mn, Fe, Os, Co, Rh, Ru, Ir, Ce, Pr, Nd, Pm,
Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm Yb, Lu, Ac, U, Lu, Ac, Th, Pa, U,
Np, Pu, Am, and Cm. Metal atoms capable of having an oxidation
state of +4 include, but are not limited to, Ti, Zr, Hf, V, Nb, Ta,
Mn, Zr, Mo, Ru, Rh, Pd, Sn, Hf, W, Re, Os, Ir, Pt, Pb, Ce, Pr, Th,
U, Pr, Th, Pa, U, Np, and Pu. Metal atoms capable of having an
oxidation state of +5 include, but are not limited to, V, Nb, Mo,
Ta, W, Pa, U, and Np. Metal atoms capable of having an oxidation
state of +6 include, but are not limited to, Mn, Mo, Ru, W, Re, Os,
Ir, and U.
[0111] "Conformal layer" refers to the physical characteristics of
a layer of deposited material on a substrate or a feature of a
substrate. Conformal layers preferably lack gaps or voids having a
volume larger than about 10.sup.-6 .mu.m.sup.3 within the bulk
phase of the conformal layer or positioned between the layer and
the surfaces of a feature coated by the layer. Conformal layers
have uniform thickness at any surface of the feature (with
variation less than about 20%). Conformal layers in the present
invention may have a uniform composition throughout the layer or
may have a composition that varies through all or a portion of the
layer. The term "superconformal" refers to the result in which the
thickness of coating on the sidewall proximate to the bottom of the
feature is larger than the thickness of coating on a surface
immediately outside of the feature adjacent to its opening.
[0112] Alkyl groups include straight-chain, branched and cyclic
alkyl groups. Alkyl groups include those having from 1 to 30 carbon
atoms. Alkyl groups include small alkyl groups having 1 to 3 carbon
atoms. Alkyl groups include medium length alkyl groups having from
4-10 carbon atoms. Alkyl groups include long alkyl groups having
more than 10 carbon atoms, particularly those having 10-30 carbon
atoms. Cyclic alkyl groups include those having one or more rings.
Cyclic alkyl groups include those having a 3-, 4-, 5-, 6-, 7-, 8-,
9- or 10-member carbon ring and particularly those having a 3-, 4-,
5-, 6-, or 7-member ring. The carbon rings in cyclic alkyl groups
can also carry alkyl groups. Cyclic alkyl groups can include
bicyclic and tricyclic alkyl groups. Alkyl groups are optionally
substituted. Substituted alkyl groups include among others those
which are substituted with aryl groups, which in turn can be
optionally substituted. Specific alkyl groups include methyl,
ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, s-butyl,
t-butyl, cyclobutyl, n-pentyl, branched-pentyl, cyclopentyl,
n-hexyl, branched hexyl, and cyclohexyl groups, all of which are
optionally substituted. Substituted alkyl groups include fully
halogenated or semihalogenated alkyl groups, such as alkyl groups
having one or more hydrogens replaced with one or more fluorine
atoms, chlorine atoms, bromine atoms and/or iodine atoms.
[0113] Alkenyl groups include straight-chain, branched and cyclic
alkenyl groups. Alkenyl groups include those having 1, 2 or more
double bonds and those in which two or more of the double bonds are
conjugated double bonds. Alkenyl groups include those having from 2
to 20 carbon atoms. Alkenyl groups include small alkenyl groups
having 2 to 3 carbon atoms. Alkenyl groups include medium length
alkenyl groups having from 4-10 carbon atoms. Alkenyl groups
include long alkenyl groups having more than 10 carbon atoms,
particularly those having 10-20 carbon atoms. Cyclic alkenyl groups
include those having one or more rings. Cyclic alkenyl groups
include those in which a double bond is in the ring or in an
alkenyl group attached to a ring. Cyclic alkenyl groups include
those having a 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-member carbon ring
and particularly those having a 3-, 4-, 5-, 6- or 7-member ring.
The carbon rings in cyclic alkenyl groups can also carry alkyl
groups. Cyclic alkenyl groups can include bicyclic and tricyclic
alkyl groups. Alkenyl groups are optionally substituted.
Substituted alkenyl groups include among others those which are
substituted with alkyl or aryl groups, which groups in turn can be
optionally substituted. Specific alkenyl groups include ethenyl,
prop-1-enyl, prop-2-enyl, cycloprop-1-enyl, but-1-enyl, but-2-enyl,
cyclobut-1-enyl, cyclobut-2-enyl, pent-1-enyl, pent-2-enyl,
branched pentenyl, cyclopent-1-enyl, hex-1-enyl, branched hexenyl,
cyclohexenyl, all of which are optionally substituted. Substituted
alkenyl groups include fully halogenated or semihalogenated alkenyl
groups, such as alkenyl groups having one or more hydrogens
replaced with one or more fluorine atoms, chlorine atoms, bromine
atoms and/or iodine atoms.
[0114] Aryl groups include groups having one or more 5- or 6-member
aromatic or heteroaromatic rings. Aryl groups can contain one or
more fused aromatic rings. Heteroaromatic rings can include one or
more N, O, or S atoms in the ring. Heteroaromatic rings can include
those with one, two or three N, those with one or two 0, and those
with one or two S, or combinations of one or two or three N, O or
S. Aryl groups are optionally substituted. Substituted aryl groups
include among others those which are substituted with alkyl or
alkenyl groups, which groups in turn can be optionally substituted.
Specific aryl groups include phenyl groups, biphenyl groups,
pyridinyl groups, and naphthyl groups, all of which are optionally
substituted. Substituted aryl groups include fully halogenated or
semihalogenated aryl groups, such as aryl groups having one or more
hydrogens replaced with one or more fluorine atoms, chlorine atoms,
bromine atoms and/or iodine atoms.
[0115] Arylalkyl groups are alkyl groups substituted with one or
more aryl groups wherein the alkyl groups optionally carry
additional substituents and the aryl groups are optionally
substituted. Specific alkylaryl groups are phenyl-substituted alkyl
groups, e.g., phenylmethyl groups. Alkylaryl groups are
alternatively described as aryl groups substituted with one or more
alkyl groups wherein the alkyl groups optionally carry additional
substituents and the aryl groups are optionally substituted.
Specific alkylaryl groups are alkyl-substituted phenyl groups such
as methylphenyl. Substituted arylalkyl groups include fully
halogenated or semihalogenated arylalkyl groups, such as arylalkyl
groups having one or more alkyl and/or aryl having one or more
hydrogens replaced with one or more fluorine atoms, chlorine atoms,
bromine atoms and/or iodine atoms.
[0116] Optional substitution of any alkyl, alkenyl and aryl groups
includes substitution with one or more of the following
substituents: halogens, --CN, --COOR, --OR, --COR, --OCOOR,
--CON(R).sub.2, --OCON(R).sub.2, --N(R).sub.2, --NO.sub.2, --SR,
--SO.sub.2R, --SO.sub.2N(R).sub.2 or --SOR groups. Optional
substitution of alkyl groups includes substitution with one or more
alkenyl groups, aryl groups or both, wherein the alkenyl groups or
aryl groups are optionally substituted. Optional substitution of
alkenyl groups includes substitution with one or more alkyl groups,
aryl groups, or both, wherein the alkyl groups or aryl groups are
optionally substituted. Optional substitution of aryl groups
includes substitution of the aryl ring with one or more alkyl
groups, alkenyl groups, or both, wherein the alkyl groups or
alkenyl groups are optionally substituted.
[0117] Optional substituents for alkyl, alkenyl and aryl groups
include among others: [0118] --COOR where R is a hydrogen or an
alkyl group or an aryl group and more specifically where R is
methyl, ethyl, propyl, butyl, or phenyl groups all of which are
optionally substituted; [0119] --COR where R is a hydrogen, or an
alkyl group or an aryl groups and more specifically where R is
methyl, ethyl, propyl, butyl, or phenyl groups all of which groups
are optionally substituted; [0120] --CON(R).sub.2 where each R,
independently of each other R, is a hydrogen or an alkyl group or
an aryl group and more specifically where R is methyl, ethyl,
propyl, butyl, or phenyl groups all of which groups are optionally
substituted; R and R can form a ring which may contain one or more
double bonds; [0121] --OCON(R).sub.2 where each R, independently of
each other R, is a hydrogen or an alkyl group or an aryl group and
more specifically where R is methyl, ethyl, propyl, butyl, or
phenyl groups all of which groups are optionally substituted; R and
R can form a ring which may contain one or more double bonds;
[0122] --N(R).sub.2 where each R, independently of each other R, is
a hydrogen, or an alkyl group, acyl group or an aryl group and more
specifically where R is methyl, ethyl, propyl, butyl, or phenyl or
acetyl groups all of which are optionally substituted; or R and R
can form a ring which may contain one or more double bonds. [0123]
--SR, --SO.sub.2R, or --SOR where R is an alkyl group or an aryl
groups and more specifically where R is methyl, ethyl, propyl,
butyl, phenyl groups all of which are optionally substituted; for
--SR, R can be hydrogen; [0124] --OCOOR where R is an alkyl group
or an aryl groups; [0125] --SO.sub.2N(R).sub.2 where R is a
hydrogen, an alkyl group, or an aryl group and R and R can form a
ring; [0126] --OR where R.dbd.H, alkyl, aryl, or acyl; for example,
R can be an acyl yielding --OCOR* where R* is a hydrogen or an
alkyl group or an aryl group and more specifically where R* is
methyl, ethyl, propyl, butyl, or phenyl groups all of which groups
are optionally substituted;
[0127] Specific substituted alkyl groups include haloalkyl groups,
particularly trihalomethyl groups and specifically trifluoromethyl
groups. Specific substituted aryl groups include mono-, di-, tri,
tetra- and pentahalo-substituted phenyl groups; mono-, di-, tri-,
tetra-, penta-, hexa-, and hepta-halo-substituted naphthalene
groups; 3- or 4-halo-substituted phenyl groups, 3- or
4-alkyl-substituted phenyl groups, 3- or 4-alkoxy-substituted
phenyl groups, 3- or 4-RCO-substituted phenyl, 5- or
6-halo-substituted naphthalene groups. More specifically,
substituted aryl groups include acetylphenyl groups, particularly
4-acetylphenyl groups; fluorophenyl groups, particularly
3-fluorophenyl and 4-fluorophenyl groups; chlorophenyl groups,
particularly 3-chlorophenyl and 4-chlorophenyl groups; methylphenyl
groups, particularly 4-methylphenyl groups, and methoxyphenyl
groups, particularly 4-methoxyphenyl groups.
[0128] As to any of the above groups which contain one or more
substituents, it is understood, that such groups do not contain any
substitution or substitution patterns which are sterically
impractical and/or synthetically non-feasible. In addition, the
compounds of this invention include all stereochemical isomers
arising from the substitution of these compounds.
[0129] The compounds of this invention may contain one or more
chiral centers. Accordingly, this invention is intended to include
racemic mixtures, diasteromers, enantiomers and mixture enriched in
one or more steroisomer. The scope of the invention as described
and claimed encompasses the racemic forms of the compounds as well
as the individual enantiomers and non-racemic mixtures thereof.
[0130] An objective of the current invention is to provide a
process for the preparation of volatile metal complexes containing
N,N-(disubstituted)diboranamide ("diboranamide") or
P,P-(disubstituted)diboranaphosphide ("diboranaphosphide") groups,
which are useful for chemical vapor deposition (CVD) of metal
diborides or metal-containing films on substrates. The diboranamide
group is defined here as a group with the charge of -1, in which
two BH.sub.3 units and two organic substituents are bound to a
central nitrogen atom. The diboranaphosphide group is defined here
as a group with the charge of -1, in which two BH.sub.3 units and
two organic substituents are bound to a central phosphorus atom. In
one aspect, the present invention relates to a method of depositing
metal-containing layers on substrates by vaporizing and decomposing
metal complexes of formula F1.
[0131] The present invention provides novel metal complexes
containing N,N-(disubstituted)diboranamide ("diboranamide") or
P,P-(disubstituted)diboranaphosphide ("diboranaphosphide") groups,
which are useful for chemical vapor deposition (CVD) of metal
diborides or other metal-containing films on substrates. Novel
reactions to prepare the metal complexes of these groups are also
provided. The diboranamide group is defined here organic groups
with the charge of -1, in which two BH.sub.3 groups and two organic
substituents are bound to a central nitrogen atom. The
diboranaphosphide group is defined here as a group with the charge
of -1, in which two BH.sub.3 units and two organic substituents are
bound to a central phosphorus atom.
[0132] Some of the ligands of formula F2 are known to those skilled
in the art. For example, the ligand L in the compounds of formula
F2, where R.sup.1 and R.sup.2 are the methyl groups, has been
reported by A. B. Burg et. al. (Inorg, Chem. 1965, 4, 1467), C.
Keller et. al. (Inorg. Chem. 1971, 10, 2256) and H. Noth et. al.
(Eur. J. Inorg. Chem. 1999, 1373). The compounds of formula I may
be prepared in a variety of suitable ways. One method to prepare
the compounds of formula I, for example, is treating sodium
N,N-dialkyldiboranamides with metal halide compounds followed by
subliming the products from the reaction mixtures.
[0133] The solvents that are suitable for preparation of the
compounds of present invention can be one or more of the
followings: no solvent (solventless solid state reaction), ethers,
polyethers, cyclic ethers, thiothers, amines (aliphatic or
aromatic, primary, secondary, or tertiary), polyamines, nirtiles,
cyanates, isocyanates, thiocyanates, esters, aldehydes, toulene,
saturated or unsaturated hydrocarbons (linear, branched, or
cyclic), halogenated hydrocarbons, silylated hydrocarbons, amides
or compounds containing combinations of any of the above, or
mixtures of one or more of the above. In a preferred embodiment,
the solvent system includes, for example, solventless solid state
reaction system, solid state reaction under non-coordinating
solvents (e.g. pentane, toluene, or halogenated hydrocarbon),
ethers (e.g., diethylether), polyethers (e.g., dimethoxyethane),
and cyclic ethers (e.g., tetrahydrofuran). The product may be
isolated from the reaction mixture in many different ways
including, for example, sublimation, or crystallization from the
solution containing products. Typically, highly pure product is
isolated by sublimation from crystallized solid product.
[0134] Any suitable method using the volatile compound of formula I
can be used to prepare metal-containing films. The metal complexes
of formula I in the present invention may be introduced onto a
substrate as a vapor, decompose and form a layer containing one or
more metals in the form of a metal-containing film. A metal complex
is preferably delivered and decomposed as a vapor in CVD, ALD, or
molecular beam epitaxy (MBE). The decomposition of metal complexes
in CVD, ALD, or MBE processes affords layers containing one or more
metals on substrates. Metal borides, metal borocarbides, or metal
boron-carbonitrides are deposited if the metal complexes are
decomposed under inert condition in which no other vapor except the
metal complex vapor or inert gas such as argon. If the
decomposition is carried out under an oxidizing atmosphere in which
gas molecules containing oxygen such as water, oxygen, ozone,
carbon dioxide or nitrogen dioxide is present, metal oxides are
formed. When amine species such as ammonia or hydrazine are used as
gaseous co-reactants, layers containing metals in the form of
nitrides, boronitrides, or borocarbo-nitrides are deposited. In one
embodiment of the invention, the metal complexes in this invention
may be used as dopants in small amounts in other phases: for
example, the magnesium compound of formula I may be used as a
magnesium dopant in the preparation of p-type semiconductor
materials such as GaN and AlGaN.
[0135] An apparatus for the deposition of layers from gaseous metal
complexes is typically pressure tight and can be evacuated. Thus,
deposition processes are typically carried out under reduced
pressure and the metal complexes are transported into the apparatus
as vapors. Inert or reactive carrier gases, or other gaseous
co-reactants can also be introduced into the apparatus.
Decomposition of the precursors on a substrate is conducted by
known methods such as thermal decomposition, plasma or
radiation-induced decomposition, or photolytic decomposition. The
principles of processes and apparatus for the deposition of films
are well known in the art.
[0136] The vaporization of precursors may be carried out by
conventional vaporization methods from solid precursors. The
vaporization methods may also include the nebulization of solid
precursors, where before the nebulization, solid precursors may be
dissolved in organic solvents, including hydrocarbons such as
decane, dodecane, tetradecane, toluene, xylene and mesitylene, and
ethers, esters, ketones, and chlorinated hydrocarbons. The
precursor solution may also be delivered onto a substrate by direct
injection of the solutions. A carrier gas that is passed through or
over the precursor may be used to enhance the vaporization of the
precursor especially when higher precursor flux is needed.
[0137] The present invention will be further illustrated by the
following non-limiting examples. The particular materials, amounts,
conditions, and other details in these examples should not be
construed to limit the scope of the present invention to their
details.
[0138] All experiments were carried out under vacuum or under argon
by using standard Schlenk techniques. Solvents were distilled under
nitrogen from sodium/benzophenone immediately before use. The
starting material Na(H.sub.3BNMe.sub.2BH.sub.3) was prepared by the
method of H Noth et al., Eur. J. Inorg. Chem. 8, 1383 (1999).
TiCl.sub.3(thf).sub.3, VCl.sub.3(thf).sub.3, CrCl.sub.3(thf).sub.3,
MoCl.sub.3(thf).sub.3 were prepared by literature procedures.
MnCl.sub.2 was dried with thionyl chloride. MgBr.sub.2, YCl.sub.3,
and DyCl.sub.3 were used as received from Aldrich. All metal
compounds produced by the following procedures are often
pyrophoric. They should be handled with strict exclusion of air and
moisture in a well-ventilated fume hood. The IR spectra were
recorded on a Nicolet Impact 410 instrument as Nujol mulls. The
.sup.1H and .sup.11B NMR data were collected on Varian Unity Inova
600 instrument at 599.761 and 192.432 MHz, respectively. Chemical
shifts are reported in .delta. units (positive shifts to high
frequency) relative to tetramethylsilane (.sup.1H NMR) or
BF.sub.3.Et.sub.2O (.sup.11B NMR). Field desorption (FD) and field
ionization (FI) mass spectra were recorded on a Micromass 70-VSE
mass spectrometer; for FD spectra, the samples were loaded as
C.sub.6H.sub.6 solutions and the spectrometer source temperature
was slowly warmed to 100.degree. C. while collecting the data. The
shapes of all peak envelopes correspond with those calculated from
the natural abundance isotopic distributions. Magnetic moments were
determined in C.sub.6D.sub.6 by the Evans NMR method on a Varian
Gemini 500 instrument at 499.699 MHz.
Example 1
Synthesis of bis(N,N-dimethyldiboranamido) magnesium(II),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0139] MgBr.sub.2 powder (1.94 g, 10.5 mmol) and sodium
dimethyldiboranamide (2.0 g, 21.0 mmol) were combined and mixed
with the use of a mortar and pestle. The ground reaction mixture
was transferred in a 100 round-bottom Schlenk flask. The Schlenk
flask was capped with a water-cooled cold finger and evacuated.
Sublimation under static vacuum afforded colorless product over 8
hours.
[0140] Yield: 1.13 g (64%). Sublimation: 20-70.degree. C. at 0.05
Torr. Vapor pressure at 20.degree. C.: 0.8.+-.0.1 torr. Mp:
70.degree. C. .sup.1H NMR (C.sub.7D.sub.8, 20.degree. C.): .delta.
2.04 (s, 12H, NMe.sub.2), 1.91 (q, J.sub.BH=90.0 Hz, 12H,
BH.sub.3). .sup.13C{.sup.1H} NMR (C.sub.7D.sub.8, 20.degree. C.):
.delta. 50.98 (s, NMe.sub.2). Anal. Calcd for
C.sub.4H.sub.24N.sub.2B.sub.4Mg: C, 28.6; H, 14.4; N, 16.6; B,
25.8; Mg, 14.5. Found: C, 28.6; H, 15.1; N, 16.6, B, 25.7; Mg,
14.1.
[0141] The molecular structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, which was determined by single
crystal X-ray crystallography, is shown in FIG. 1.
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is a monomeric compound in
which two [H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands coordinate to
the magnesium center by means of eight Mg to hydrogen bonds. All
Mg-H distances are equal within experimental error, averaging 2.02
.ANG. and the two diboranamide ligands describe a dihedral angle of
46.7.degree.
Example 2
Synthesis of
bis(N,N-dimethyldiboranamido)(tetrahydrofuran)magnesium(II),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf)
[0142] To a suspension of MgBr.sub.2 (0.51 g, 2.8 mmol) in thf (20
ml) at room temperature was added a solution of
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.53 g, 5.6 mmol) in thf (30 ml).
After the reaction mixture had been stirred for 8 h at room
temperature, the solvent was removed in vacuum. Colorless solid was
isolated as a product by sublimation.
[0143] Yield: 0.31 g (47%). Sublimation: 70.degree. C. at 0.05
Torr. .sup.1H NMR (C.sub.7D.sub.8, 20.degree. C.): .delta. 3.57 (m,
4H, OCH.sub.2), 2.33 (s, 12H, NMe.sub.2), 1.99 (q, J.sub.BH=84.5
Hz, 12H, BH.sub.3), 1.28 (m, 4H, OCH.sub.2CH.sub.2).
.sup.13C{.sup.1H} NMR (C.sub.7D.sub.8, 20.degree. C.): .delta. 69.2
(s, OCH.sub.2), 52.4 (s, NCH.sub.3), 25.5 (s, OCH.sub.2CH.sub.2).
Anal. Calcd for C.sub.8H.sub.32N.sub.2B.sub.40 Mg: C, 40.1; H,
13.4; N, 11.7; B, 18.0; Mg, 10.1. Found: C, 39.5; H, 13.3; N, 11.3;
B, 16.0; Mg, 10.5.
Example 3
Synthesis of
bis(N,N-dimethyldiboranamido)(1,2-dimethoxyethane)magnesium(II),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme)
[0144] The synthesis of this compound is similar to that of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf) in Example 2, using
1,2-dimethoxyethane instead of thf. Colorless crystals were
obtained by sublimation.
[0145] Yield: 0.27 g (37%). Sublimation: 80.degree. C. at 0.05
Torr. .sup.1H NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 3.00 (s,
6H, OMe), 2.81 (s, 4H, OCH.sub.2), 2.48 (s, 12H, NMe.sub.2), 2.11
(q, J.sub.BH=88.5 Hz, 12H, BH.sub.3). .sup.13C{.sup.1H} NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. 69.6 (s, OCH.sub.2), 59.6
(s, OCH.sub.3), 52.6 (s, NMe.sub.2). Anal. Calcd for
C.sub.8H.sub.34N.sub.2B.sub.4O.sub.2Mg: C, 37.3; H, 13.3; N, 10.9;
B, 16.8; Mg, 9.42. Found: C, 36.4; H, 13.2; N, 10.4; B, 17.1; Mg,
9.92.
Example 4
Synthesis of bis(N,N-dimethyldiboranamido)titanium(II),
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0146] To a suspension of TiCl.sub.3(thf).sub.3 (1.31 g, 3.5 mmol)
in diethyl ether (20 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (1.01 g, 10.6 mmol) in diethyl
ether (40 mL). The reaction mixture was stirred at 0.degree. C. for
50 min and was allowed to warm to room temperature and stirred for
5 h. Gas slowly evolved. A blue-green solution and a white
precipitate formed. The blue-green solution was filtered,
concentrated to ca. 10 mL, and cooled to -20.degree. C. to afford
blue-green crystals.
[0147] Yield: 0.58 g (86%). The product can also be further
purified by sublimation at 45.degree. C. and 0.05 Torr. Anal. Calcd
for C.sub.4H.sub.24N.sub.2B.sub.4Ti: C, 25.1; H, 12.6; N, 14.6; B,
22.6; Ti, 25.0. Found: C, 24.4; H, 12.8; N, 13.8; B, 22.0; Ti,
25.0. MS (FI): m/z 192.2 (M.sup.+). .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 13.2 (s, fwhm=650 Hz, NMe). Magnetic moment
(C.sub.6D.sub.6, 20.degree. C.): 2.6.mu..sub.B.
[0148] Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, shown in FIG. 2, is a
monomeric compound that contains two
[H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands binding to the titanium
center by means of eight Ti-H contacts. Unlike the
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, the two diboranamide ligands
are coplanar, describing a dihedral angle of 0.degree.. The Ti-H
distances are identical within the experimental error at 2.005 and
2.034 .ANG..
Example 5
Synthesis of bis(N,N-dimethyldiboranamido)chromium(II),
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0149] Following a similar procedure as described above for the
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 complex, but using
CrCl.sub.3(thf).sub.3, blue crystalline solids were obtained as a
product by the removal of the solvent from the reaction mixture
followed by sublimation.
[0150] Yield: 0.18 g (34%). Sublimation: 40.degree. C. at 0.05
Torr. Anal. Calcd for C.sub.4H.sub.24N.sub.2B.sub.4Cr: C, 24.6; H,
12.4; N, 14.3; B, 22.1; Cr, 26.6. Found: C, 24.7; H, 12.2; N, 14.3;
B, 22.7; Cr, 25.1. MS (FI): m/z 196.2 (M.sup.+). .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. 43.6 (s, fwhm=400 Hz,
NMe). Magnetic moment (C.sub.6D.sub.6, 20.degree. C.):
4.8.mu..sub.B. The molecular geometry of
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is essentially identical to
that of Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
Example 6
Synthesis of bis(N,N-dimethyldiboranamido)molybdenum(II),
Mo(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0151] Following a similar procedure as described above for the
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, but using
MoCl.sub.3(thf).sub.3, green crystalline solids were obtained as a
product by the removal of the solvent from the reaction mixture
followed by sublimation.
[0152] Yield: 0.18 g (28%). Sublimation: 70.degree. C. at 0.05
Torr. MS (FD): m/z 239.2 (M.sup.+). Anal. Calcd for
C.sub.4H.sub.24N.sub.2B.sub.4Mo: C, 20.1; H, 10.1; N, 11.7; B,
18.1; Mo, 40.1. Found: C, 20.4; H, 10.1; N, 12.2; B, 17.7; Mo,
39.6. .sup.1H{.sup.11B} NMR (CD.sub.2Cl.sub.2, 20.degree. C.):
.delta. 4.93 (t, J.sub.HH=9.3 Hz, 4H, BH), 2.68 (s, 12H,
NMe.sub.2), 6.75 (d, J.sub.HH=9 Hz, 8H, MoHB). .sup.11B{.sup.1H}
NMR: 25.24 (s). IR (cm.sup.-1): 2438 vs, 2192 w, 2153 w, 2126 w,
2014 w, 1925 s, 1865 vs, 1765 m, 1731 m, 1335 s, 1306 s, 1241 s,
1217 s, 1152 s, 1092 vs, 1028 s, 975 s, 939 m, 912 m, 807 s.
[0153] A second species is present in the solutions, with NMR peak
intensities that are 29% of those for the major species. .sup.1H
NMR: .delta. 4.55 (t, J.sub.HH=9.6 Hz, 4H, BH), 2.72 (s, 12H,
NMe.sub.2), 6.74 (d, J.sub.HH=9 Hz, 8H, MoHB). .sup.11B{.sup.1H}
NMR: 24.43 (s).
[0154] The molecular geometry of Mo(DMDBA).sub.2 is essentially the
same as that for Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
Example 7
Synthesis of bis(N,N-dimethyldiboranamido)manganese(II),
Mn(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0155] Following a similar procedure as described above for the
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, but using MnCl.sub.2, light
yellow crystalline solids were obtained as a product by the removal
of the solvent from the reaction mixture followed by
sublimation.
[0156] Yield: 0.25 g (29%). Sublimation: 50.degree. C. at 0.05
Torr. Anal. Calcd for C.sub.4H.sub.24N.sub.2B.sub.4Mn: C, 24.2; H,
12.2; N, 14.1. Found: C, 24.2; H, 12.3; N, 14.2. MS (FI): m/z 197.2
((M-2).sup.+). .sup.1H NMR (C.sub.6D.sub.6, 20.degree. C.): .delta.
46.8 (s, fwhm=3200 Hz, NMe.sub.2). Magnetic moment (C.sub.6D.sub.6,
20.degree. C.): 5.9.mu..sub.B. The molecular geometry of the
Mn(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is essentially identical to
that of Mn(H.sub.3BNMe.sub.2BH.sub.3).sub.2 with a dihedral angle
of 46.5.degree. between the two diboranamide ligands.
Example 8
Synthesis of hexa(N,N-dimethyldiboranamido)diyttrium(III),
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6
[0157] Following a similar procedure as described above for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, but using YCl.sub.3, off-white
solids were obtained as a product by sublimation.
[0158] Yield: 0.22 g (19%). Sublimation: 100.degree. C. at 0.05
Torr. .sup.1H NMR (CD.sub.2Cl.sub.2, 20.degree. C.): .delta. 2.42
(s, 36H, NMe.sub.2), 2.06 (q, J.sub.BH=84 Hz, 36H, BH.sub.3).
.sup.13C{.sup.1H} NMR (CD.sub.2Cl.sub.2, 20.degree. C.): .delta.
51.14 (s, CH.sub.3). .sup.11B{.sup.1H} NMR (CD.sub.2Cl.sub.2,
20.degree. C.): .delta. 50.83 (s, BH.sub.3). Anal. Calcd for
C.sub.6H.sub.36N.sub.3B.sub.6Y: C, 23.7; H, 11.9; N, 12.8; B, 21.3;
Y, 29.2. Found: C, 22.9; H, 11.1; N, 12.8; B, 19.5; Y, 28.0.
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, shown in FIG. 3, is a
dimeric compound in which each yttrium center contains two
[H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands and two
[H.sub.3BNMe.sub.2BH.sub.3] ligands bridge between two yttrium
centers.
Example 9
Synthesis of
tris(dimethyldiboranamido)(tetrahydrofuran)yttrium(III),
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf)
[0159] Following a similar procedure as described above for the
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 complex, but using YCl.sub.3
and solvent thf, off-white solids were obtained as a product by the
removal of the solvent from the reaction mixture followed by
sublimation.
[0160] Yield: 0.76 g (37%). Sublimation: 90.degree. C. at 0.05
Torr. .sup.1H NMR (CD.sub.2Cl.sub.2, 20.degree. C.): .delta. 3.98
(m, 4H, OCH.sub.2), 2.37 (s, 18H, NMe.sub.2), 2.00 (q, J.sub.BH=84
Hz, 18H, 8H.sub.3), 1.90 (m, 4H, CH.sub.2). Anal. Calcd for
C.sub.10H.sub.44N.sub.3B.sub.6O.sub.1Y: C, 31.9; H, 11.8; N, 11.2.
Found: C, 30.1; H, 11.8; N, 11.5.
Example 10
Synthesis of hexa(N,N-dimethyldiboranamido)didysprosium(III),
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6
[0161] Following a similar procedure as described above for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, but using DyCl.sub.3,
off-white solids were obtained as a product by sublimation.
[0162] Yield: 0.19 g (24%). Sublimation: 90.degree. C. at 0.05
Torr. Anal. Calcd for C.sub.6H.sub.36N.sub.3B.sub.6Dy: C, 19.1; H,
9.61; N, 11.1. Found: C, 19.0; H, 9.62; N, 10.8. MS (FI): m/z 377.3
(M-1).sup.+. .sup.1H NMR (C.sub.6D.sub.6, 20 (C): .delta. 97.5 (s,
fwhm=250 Hz, NMe.sub.2). The molecular geometry of
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 is the same as that for
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
Example 11
Synthesis of Tris(dimethyldiboranamido)(thf)dysprosium(III),
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf)
[0163] Following a similar procedure as described above for
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, but using DyCl.sub.3,
colorless crystals were obtained as a product by extraction with
pentane followed by crystallization at -20.degree. C.
[0164] Yield: 0.47 g (63%). Sublimation: 90.degree. C. at 0.05
Torr. .sup.1H NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. -19.50
(s, fwhm=250 Hz, 18H, NMe.sub.2); -29.07 (s, fwhm=150 Hz, 4H,
--CH.sub.2CH.sub.2-- in thf). Anal. Calcd for
C.sub.10H.sub.44N.sub.3B.sub.6O.sub.1Dy: C, 26.7; H, 9.86; N, 9.34;
B, 14.4; Dy, 36.1. Found: C, 26.1; H, 10.1; N, 8.73; B, 15.0; Dy,
33.8.
Example 12
Volatile Magnesium Octahydrotriborate Complexes as Potential CVD
Precursors to MgB.sub.2. Synthesis and Characterization of
MgB.sub.3H.sub.8).sub.2 and its Etherates
Introduction
[0165] Magnesium diboride (MgB.sub.2) has been the subject of
considerable interest since the discovery in 2001 that it becomes
superconducting at 39 K..sup.1 MgB.sub.2 has highly attractive
properties for applications in superconducting electronics: in
addition to having the highest critical temperature of all
intermetallic superconductors, it has a long coherence length of
ca. 5 nm and a high critical current density..sup.2-4 These
properties suggest that MgB.sub.2-based superconducting circuits
should operate more rapidly, and at a higher temperature, than
circuits based on niobium alloys.
[0166] Because multilayer tunneling junctions are core elements in
integrated circuits, intensive research has been directed toward
the development of methods to grow high-quality MgB.sub.2 thin
films. Successful depositions of such films have been achieved by
co-evaporation of Mg and B in extremely clean environments,.sup.5
by boron deposition followed by ex-situ annealing with Mg vapor in
a sealed tube,.sup.6 and by a hybrid physical-chemical vapor
deposition (HPCVD) technique in which B.sub.2H.sub.6 reacts with Mg
vapor..sup.7 Methodological improvements are still required,
however, to achieve the large-scale fabrication of multilayer
MgB.sub.2 tunneling junctions, which require the deposition of
stoichiometric, crystalline films via an in-situ process at a low
temperature. No purely chemical vapor deposition (CVD) route to
MgB.sub.2 films has been described. One obstacle is that magnesium
tends to evaporate from the growth surface at temperatures above
0.425.degree. C.,.sup.8 leaving behind boron or boron-rich
films.
[0167] Another obstacle to preparing MgB.sub.2 by CVD is that few
magnesium compounds are volatile and, of those, none has been shown
to be chemically suited as a precursor for this phase. Although
magnesium complexes of tetrahydroborate (BH.sub.4.sup.-),
octahydrotriborate (B.sub.3H.sub.8.sup.-), and nonahydrohexaborate
(B.sub.6H.sub.9.sup.-) groups have been described, all are
nonvolatile. Specifically, the binary complex Mg(BH.sub.4).sub.2 is
known,.sup.9 as are several Lewis base adducts,
Mg(BH.sub.4).sub.2L.sub.x (L=ethers, amines, or
sulfoxides)..sup.10-13 For the higher boron hydrides, ionic species
of the form [Mg(L).sub.6][B.sub.3H.sub.8].sub.2, where L is
NH.sub.3, thf, or 1/3 diglyme, can be prepared by reaction of
Mg(BH.sub.4).sub.2L.sub.x with diborane,.sup.14-16 and
Mg(B.sub.6H.sub.9).sub.2(thf).sub.2 can be prepared by reaction of
MgMe.sub.2 or MeMgBr with B.sub.6H.sub.10 in thf..sup.17
[0168] We now describe the synthesis of
bis(octahydrotriborate)magnesium Mg(B.sub.3H.sub.8).sub.2 and its
Lewis base adducts, Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 and
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2. These molecules are
volatile and are the first crystallographically characterized
magnesium complexes of the B.sub.3H.sub.8 ligand. Owing to their
volatility, Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 and
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2 are potential precursors
for the deposition of MgB.sub.2 thin films, and we describe
preliminary efforts to grow thin films from them under CVD
conditions. These new compounds closely resemble other volatile
MB.sub.xH.sub.y precursors that are known to afford high qualify
films of metal diboride materials such as TiB.sub.2, CrB.sub.2,
ZrB.sub.2, and HfB.sub.2..sup.18-22
Results and Discussion
[0169] Synthesis and Characterization of
Mg(B.sub.3H.sub.8).sub.2.
[0170] If the reaction of MgBr.sub.2 and NaB.sub.3H.sub.8 is
carried out in ether solvents (diethyl ether, tetrahydrofuran, or
dimethoxyethane), the reaction products are non-volatile. Previous
work suggests that the presence of excess solvent results in the
formation of ionic magnesium compounds: the reactions of
Mg(BH.sub.4).sub.2 with B.sub.2H.sub.6 in thf or diglyme afford the
salts [Mg(thf).sub.6][B.sub.3H.sub.8].sub.2.sup.14 and
[Mg(diglyme).sub.2][B.sub.3H.sub.8].sub.2,.sup.15 in which the
magnesium dications are exclusively coordinated to ether molecules.
The ionic nature of these latter materials is shown by the absence
of Mg-H-B stretching bands near 2300 cm.sup.-1 in their IR spectra.
Similarly, Lewis base adducts of Mg(BH.sub.4).sub.2 have different
structures depending on the stoichiometry: the 3:1 complexes
Mg(BH.sub.4).sub.2L.sub.3 (L=thf, tert-butylamine, or piperidine)
and the 4:1 complex Mg(BH.sub.4).sub.2(pyridine).sub.4 are
monomeric, but the 6:1 adducts [MgL.sub.6][BH.sub.4].sub.2
(L=benzylamine or dimethyl sulfoxide) are ionic
salts..sup.10,12
[0171] A key to the synthesis of volatile magnesium B.sub.3H.sub.8
complexes is the use of reaction methods that avoid the use of a
solvent. Thus, the solid state reaction of MgBr.sub.2 and
NaB.sub.3H.sub.8 at 20.degree. C., followed by sublimation at
80.degree. C. and 0.05 Torr, affords the new compound
Mg(B.sub.3H.sub.8).sub.2 (1) as a white solid. Attempts to obtain
single crystals of 1 suitable for X-ray diffraction have been
unsuccessful.
[0172] The infrared spectrum of 1 (FIG. 4) contains two terminal
B-H stretches at 2543 and 2479 cm.sup.-1, one bridging Mg-H-B
stretch at 2316 cm.sup.-1 and a bridging B-H-B stretch at 2175
cm.sup.-1. All of these bands are consistent with the presence of
coordinated B.sub.3H.sub.8 groups. The B-H stretching bands for 1
are similar to those observed for transition metal
octahydrotriborate complexes.sup.19,23-25 with two exceptions.
First, the 2316 cm.sup.-1 frequency for the M-H-B stretching band
is higher than those of 2000-2200 cm.sup.-1 seen for transition
metal B.sub.3H.sub.8 complexes;.sup.24,25 The higher frequency seen
in 1 reflects the lower mass of the magnesium atom and the less
covalent character of the Mg-B.sub.3H.sub.8 interaction. Second,
the 2316 cm.sup.-1 band is more intense than the M-H-B stretching
bands seen for transition metal complexes.
[0173] Further characterization of 1 (for example, by solution NMR
spectroscopy) has been precluded by the insolubility of 1 in common
organic solvents, including pentane, benzene, toluene,
dichloromethane, tetrahydrofuran, and dioxane. Protic solvent such
as ethanol and water react with 1, with vigorous evolution of
gas.
[0174] Synthesis and Characterization of
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 and
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2.
[0175] The solid state reaction of MgBr.sub.2.Et.sub.2O and
NaB.sub.3H.sub.8 at 20.degree. C., followed by sublimation at
70.degree. C. and 0.05 Torr, yields the colorless crystalline
product, Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 (2). A similar
reaction with MgBr.sub.2(Me.sub.2O).sub.1.6 affords the dimethyl
ether analogue Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2 (3). The
IR spectrum of 2 features strong bands at 2506 and 2448 cm.sup.-1
due to terminal B-H stretches, a strong broad band at 2302
cm.sup.-1 for the Mg-H-B stretch, and a medium intensity band at
2129 cm.sup.-1 due to the B-H-B stretches (FIG. 4). The IR spectrum
of 3 in the B-H stretching region is very similar to that of 2.
[0176] Like 1, compounds 2 and 3 react with protic solvents and are
insoluble in almost all non-protic solvents; we attribute the
insolubility in strongly coordinating ethers such as
tetrahydrofuran or 1,2-dimethoxyethane to the formation of ionic
salts (see above). Compound 2 is, however, soluble in diethyl
ether. The weaker Lewis basicity of Et.sub.2O is probably
responsible for its ability to dissolve
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 without forming insoluble
ionic salts.
[0177] The .sup.1H NMR spectrum of 2 in (C.sub.2D.sub.5).sub.2O at
20.degree. C. (FIG. 5) shows a broad, unresolved signal at .delta.
0.52 for the B.sub.3H.sub.8 groups, and characteristic resonances
for the Et.sub.2O protons. The .sup.11B NMR spectrum at 20.degree.
C. contains a broad, unresolved resonance at .delta. -31.7. Similar
.sup.1H NMR and .sup.11B spectra are seen at -80.degree. C., which
suggests that the B.sub.3H.sub.8 ligand is fluxional on the NMR
time scale even at this temperature. The mass spectrum of 2
contains no parent peak (m/z=205); instead, the most intense peak
in the spectrum (m/z=318) corresponds to
Mg.sub.2(B.sub.3H.sub.8).sub.3(Et.sub.2O).sub.2.sup.+. The mass
spectrum of 3 is similar, the most intense signal (at m/z 262)
being due to
Mg.sub.2(B.sub.3H.sub.8).sub.3(Me.sub.2O).sub.2.sup.+.
[0178] The molecular structures of 2 and 3 are shown in FIGS. 6 and
7; crystallographic data, and selected bond distances and angles
are listed in Tables 1-3. The magnesium center in the diethyl ether
adduct 2 adopts a distorted cis-octahedral geometry with two
bidentate B.sub.3H.sub.8 groups and two Et.sub.2O ligands. The Mg-H
distances are identical within experimental error at 1.99(3) and
2.01(4) .ANG., and the Mg . . . B distances are nearly identical at
2.575(5) and 2.591(5) .ANG.. The B-H distances of 1.17(2) .ANG.
within the Mg-H-B units are slightly longer than the terminal B-H
distances of 1.12(3) .ANG., as expected. As seen in other metal
complexes of the bidentate B.sub.3H.sub.8.sup.-
ligand,.sup.19,26-29 the B-B distance for the non-bridged B-B bond
is the shortest at 1.779(7) .ANG., whereas B-B distances for the
two hydrogen bridged B-B bonds are slightly longer at 1.795(7) and
1.809(7) .ANG..
[0179] The Mg-H distances of 1.99(3) and 2.01(4) .ANG. in 2 lie in
the range 1.97-2.24 .ANG. seen in magnesium complexs of the
BH.sub.4 ligand..sup.9-13,30,31 The Mg . . . B distances of
2.575(5) and 2.591(5) in 2 are slightly longer than those of
2.40-2.54 .ANG. found in magnesium complexes of bidentate BH.sub.4
ligands;.sup.10-13 but are much longer than those of 2.21-2.29
.ANG. seen in magnesium complexes containing tridentate BH.sub.4
ligands,.sup.30,31 as expected.
[0180] The molecular geometry of the dimethyl ether adduct 3 is
very similar to that of 2: the magnesium center is six-coordinate
with two bidentate B.sub.3H.sub.8.sup.- ligands and two mutually
cis dimethyl ether groups. All Mg-H and Mg . . . B distances in 3
are also nearly identical to those in 2: the average Mg-H distance
is 1.96(4) .ANG., and the average Mg . . . B distance is 2.565(6)
.ANG.. The dimethyl ether ligand in 3 should be sterically less
demanding than the diethyl ether ligand in 2, and this difference
may be responsible for a subtle difference in the relative
orientations adopted by the coordinated B.sub.3H.sub.8 groups. If
we focus on the "unbound" BH.sub.2 group within each B.sub.3H.sub.8
ligand, in 3 one is proximal to the dimethyl ether group and the
other is distal, whereas in 2 both "unbound" BH.sub.2 groups are
distal to the diethyl ether ligands.
[0181] Most likely, the ether groups in 2 and 3 occupy mutually cis
positions so as to minimize interligand steric repulsions.
Interestingly, the molecular structures of 2 and 3 differ from that
of the chromium analogue
Cr(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2,.sup.19 which adopts a
trans-octahedral geometry. Electronic factors relating to the
Jahn-Teller effect dominate in determining the structure of the
d.sup.4 chromium complex: the diethyl ether ligands, which generate
the weakest ligand field splitting, are relegated to the axial
positions so as to maximize the ligand field stabilization energy.
In contrast, no such electronic factors operate in
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2.
[0182] Preliminary Attempts to Grow MgB.sub.2 Thin Films.
[0183] Deposition of thin films was carried out in an ultra high
vacuum (UHV) chamber equipped with a turbomolecular pump with the
base pressure of 5.times.10.sup.-9 Torr..sup.22 The
Mg(B.sub.3H.sub.8).sub.2 compound 1 is not an ideal precursor for
CVD because it sublimes very slowly and with some decomposition;
the ether adducts 2 and 3 sublime much more readily. For
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2 (2), the precursor
reservoir was heated to 70.degree. C. and delivered to the Si(100)
surface by means of an argon carrier gas. The onset temperature for
film growth is 400.degree. C. The resulting deposit is
non-stoichiometric, exhibiting a B/Mg ratio of 7 as determined by
Auger electron spectroscopy. For
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2 (3), the onset
temperature is 450.degree. C., and the films deposited under these
conditions consist of 70 at. % boron, 20 at. % carbon, 8 at. %
oxygen, and essentially no magnesium.
[0184] Titov et. al have reported that the solid state
decomposition of [Mg(diglyme).sub.2][B.sub.3H.sub.8].sub.2 at
185.degree. C. yields Mg(BH.sub.4).sub.2, MgB.sub.12H.sub.12,
H.sub.2, and B.sub.5H.sub.9.15 The solid state decomposition of
[Mg(NH.sub.3).sub.6][B.sub.3H.sub.8].sub.2 at 120-140.degree. C. is
reported by Levicheva to proceed somewhat differently, affording
Mg(BH.sub.4).sub.2(NH.sub.3).sub.2, B.sub.3N.sub.3H.sub.6,
(BNH).sub.n, and H.sub.2..sup.16 These findings suggest that the
thermolysis mechanism depends on the identity of the Lewis base;
thus, magnesium octahydrotriborate complexes with other neutral
ligands may be more successful in affording MgB.sub.2 by CVD (or
plasma-assisted CVD) methods.
Experimental Section
[0185] All experiments were carried out under vacuum or under argon
by using standard Schlenk techniques. Solvents were distilled under
nitrogen from sodium/benzophenone immediately before use.
NaB.sub.3H.sub.8 was prepared by a literature procedure,.sup.32 and
MgBr.sub.2 and MgBr.sub.2(Et.sub.2O) were used as received
(Aldrich). Dimethyl ether was purchased from Matheson.
Microanalyses were performed by the University of Illinois
Microanalytical Laboratory. The IR spectra were recorded on a
Nicolet Impact 410 instrument as Nujol mulls between KBr plates.
Field ionization (FI) mass spectra were recorded on a Micromass
70-VSE mass spectrometer. The shapes of all peak envelops
correspond with those calculated from the natural abundance
isotopic distributions. Melting points were determined in closed
capillaries under argon on a Thomas-Hoover Unimelt apparatus.
[0186] Bis(octahydrotriborato)magnesium(II),
Mg(B.sub.3H.sub.8).sub.2, 1.
[0187] Solid MgBr.sub.2 (2.97 g, 16.1 mmol) and NaB.sub.3H.sub.8
(1.02 g, 16.1 mmol) were ground together briefly in a mortar and
pestle. The dry mixture was transferred to a 250 mL round-bottomed
flask, and 50-60 steel balls (4.5-mm diameter) were added. The
flask was gently agitated for 30 min and over this period the solid
became slightly damp. Sublimation at 80.degree. C. under vacuum
afforded a white product. Yield: 0.16 g (19%). Mp: 120.degree. C.
(dec). Anal. Calcd for B.sub.6H.sub.16Mg: H, 15.3; B, 61.6; Mg,
23.1. Found: H, 13.0; B, 60.2; Mg, 23.1. IR (cm.sup.-1): 2543 vs,
2479 vs, 2316 vs, 2175 w, 1298 sh, 1134 vs, 1043 w, 981 vs, 829
s.
[0188] Bis(octahydrotriborato)bis(diethylether)magnesium(II),
Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, 2.
[0189] Solid MgBr.sub.2.Et.sub.2O (4.0 g, 15.5 mmol) and
NaB.sub.3H.sub.8 (1.0 g, 15.8 mmol) were ground together briefly in
a mortar and pestle. The mixture was transferred a 250 mL
round-bottomed flask, and 50-60 steel balls (4.5-mm diameter) were
added. The flask was gently agitated for 30 min and over this
period the solid became slightly damp. Sublimation at 70.degree. C.
under vacuum afforded white crystals. Yield: 0.82 g (41%). Mp.
40.degree. C. Anal. Calcd for C.sub.4H.sub.36B.sub.6O.sub.2Mg: C,
37.9; H, 14.3; B, 25.6; Mg, 9.59. Found: C, 37.5; H, 14.1; B, 25.6;
Mg, 9.71. MS (FI) (fragment ion, relative abundance): m/z 139
[Mg(B.sub.3H.sub.8)(Et.sub.2O).sup.+, 20], 213
[Mg(B.sub.3H.sub.8)(Et.sub.2O).sub.2.sup.+, 25],
[Mg.sub.3(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2.sup.+, 20], 318
[Mg.sub.2(B.sub.3H.sub.8).sub.3(Et.sub.2O).sub.2.sup.+, 100].
.sup.1H NMR (O(C.sub.2D.sub.5).sub.2, 20.degree. C.): .delta. 3.77
(q, 8H, CH.sub.2), 1.50 (t, 12H, CH.sub.3), 0.52 (br, fwmh=125 Hz,
16H, B.sub.3H.sub.8). IR (cm.sup.-1): 2506 vs, 2448 vs, 2302 vs,
2129 m, 1289 w, 1262 w, 1189 w, 1148 s, 1092 s, 1034 s, 992 s, 891
m, 865 w, 832 m, 778 s, 692 w.
[0190] Magnesium Dibromide: 1.6 Dimethylether,
MgBr.sub.2(Me.sub.2O).sub.1.6.
[0191] Solid MgBr.sub.2 (6.3 g, 34 mmol) was cooled to -78.degree.
C. and Me.sub.2O (50 mL) was condensed onto the solid. After the
mixture had been stirred for 4 h, the Me.sub.2O was removed under
vacuum to afford a white solid. Yield: 8.9 g The stoichiometry
MgBr.sub.2(Me.sub.2O).sub.1.6 was calculated by assuming that the
increase in mass of 2.5 g is contribution of Me.sub.2O (54
mmol).
[0192] Bis(octahydrotriborato)bis(dimethylether)magnesium(II),
Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2, 3.
[0193] Solid MgBr.sub.2(Me.sub.2O).sub.1.6 (1.86 g, 7.22 mmol) and
NaB.sub.3H.sub.8 (0.92 g, 14.5 mmol) were ground together briefly
in a mortar and pestle. The mixture was transferred to a 100 mL
round-bottomed flask, and 30-40 steel balls (4.5-mm diameter) were
added. The flask was gently agitated for 15 min and over this
period the solid became slightly damp. Sublimation at 75.degree. C.
under vacuum afforded white crystals. Yield: 0.25 g (25%). Mp:
55.degree. C. Anal. Calcd for C.sub.2H.sub.28B.sub.6O.sub.2Mg: C,
24.3; H, 14.3; B, 32.9; Mg, 12.3. Found: C, 23.9; H, 14.0; B, 33.1;
Mg, 13.0. MS (FI) (fragment ion, relative abundance): m/z 111
[Mg(B.sub.3H.sub.8)(Me.sub.2O).sup.+, 40],
[Mg(B.sub.3H.sub.8)(Me.sub.2O).sub.2.sup.+, 45], 216
[Mg.sub.2(B.sub.3H.sub.8).sub.3(Me.sub.2O).sup.+, 20], 262
[Mg.sub.2(B.sub.3H.sub.8).sub.3(Me.sub.2O).sub.2.sup.+, 100], 276
[Mg.sub.2(B.sub.3H.sub.8).sub.3(BH.sub.4)(Me.sub.2O).sub.2.sup.+,
15], 308 [Mg.sub.2(B.sub.3H.sub.8).sub.3(Me.sub.2O).sub.3.sup.+,
10]. IR (cm.sup.-1): 2493 vs, 2449 vs, 2301 vs, 2129 s, 1260 s,
1154 s, 1048 s, 973 w, 893 s, 812 m, 757 w.
[0194] Crystallographic Studies..sup.33
[0195] Single crystals of both compounds, grown by sublimation,
were mounted on glass fibers with Krytox oil (DuPont), and
immediately cooled to -80.degree. C. in a cold nitrogen gas stream
on the diffractometer. Data for 2 and 3 were collected with an area
detector by using the measurement parameters listed in Table 1. The
measured intensities were reduced to structure factor amplitudes
and their estimated standard deviations by correction for
background, and Lorentz and polarization effects. Systematically
absent reflections were deleted and symmetry-equivalent reflections
were averaged to yield the sets of unique data. The analytical
approximations to the scattering factors were used, and all
structure factors were corrected for both real and imaginary
components of anomalous dispersion. All structures were solved
using direct methods (SHELXTL). The correct positions for all
non-hydrogen atoms of 2 and 3 were deduced from E-maps. Final
refinement parameters for 2 and 3 are given in Table 1. A final
analysis of variance between observed and calculated structure
factors showed no apparent errors. Subsequent discussions for 2 and
3 will be divided into individual paragraphs.
[0196] (a) Mg(B.sub.3H.sub.8).sub.2(Et.sub.2O).sub.2, 2.
[0197] Although the orthorhombic lattice and systematic absences
suggested the space group P222.sub.1, the actual space group is
P2.sub.12.sub.12 with the second screw axis exhibiting weak
violations of the systematic absences, probably owing to Renninger
effects. All 1750 unique reflections were used in the least squares
refinement. Although corrections for crystal decay were
unnecessary, a face-indexed absorption correction was applied. The
quantity minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+1.22P}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. Hydrogen atoms were located in
the difference maps, and their positions were refined with
independent isotropic displacement parameters. Chemically similar
B-H and C-H distances were constrained to equal within 0.01 .ANG..
An isotropic extinction parameter was refined to a final value of
x=1.37(5).times.10.sup.-5 where F.sub.c is multiplied by the factor
k[1+F.sub.c.sup.2.times..lamda..sup.3/sin 2.theta.].sup.-1/4 with k
being the overall scale factor. Successful convergence was
indicated by the maximum shift/error of 0.000 for the last cycle.
The largest peak in the final Fourier difference map (0.20
e.ANG..sup.-3) was located 1.25 .ANG. from H13.
[0198] (b) Mg(B.sub.3H.sub.8).sub.2(Me.sub.2O).sub.2, 3.
[0199] Systematic absences for 0kl (k+l.noteq.2n) and
h0l(l.noteq.2n) were consistent with space groups Pca2.sub.1 and
Pbcm; the non-centrosymmetric Pca2.sub.1 was shown to be the
correct choice by successful refinement of the proposed model. All
2837 unique reflections were used in the least squares refinement.
Although corrections for crystal decay were unnecessary, a
face-indexed absorption correction was applied. The quantity
minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0386P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. Boron-bound hydrogen atoms were
located in the difference maps and refined without constraints;
these hydrogen atoms were each given independent isotropic
displacement parameters. Methyl hydrogen atoms were placed in
idealized tetrahedral locations with C-H=0.98 .ANG. and optimized
by rotation about C-O bonds; their displacement parameters were set
equal to 1.5 times U.sub.eq for the attached carbon. No correction
for isotropic extinction was necessary. Successful convergence was
indicated by the maximum shift/error of 0.000 for the last cycle.
The largest peak in the final Fourier difference map (0.09
e.ANG..sup.-3) was located 0.87 .ANG. from O1.
REFERENCES
[0200] 1. Nagamatsu, J.; Nakagawa, N.; Muranaka, T.; Zenitani, Y.;
Akimitsu, J. Nature 2001, 410, 63-64. [0201] 2. Xu, M.; Kitazawa,
H.; Takano, Y.; Ye, J.; Nishida, K.; Abe, H.; Matsushita, A.;
Tsujii, N.; Kido, G. Appl. Phys. Lett. 2001, 79, 2779-2781. [0202]
3. Schmidt, H.; Zasadzinski, J. F.; Gray, K. E.; Hinks, D. G. Phys.
Rev. Lett. 2002, 88. [0203] 4. Tsuda, S.; Yokoya, T.; Kiss, T.;
Takano, Y.; Togano, K.; Kito, H.; Ihara, H.; Shin, S. Phys. Rev.
Lett. 2001, 8717. [0204] 5. Ueda, K.; Naito, M. J. Appl. Phys.
2003, 93, 2113-2120. [0205] 6. Kang, W. N.; Kim, H. J.; Choi, E.
M.; Jung, C. U.; Lee, S. L. Science 2001, 292, 1521-1523. [0206] 7.
Zeng, X. H.; Pogrebnyakov, A. V.; Kotcharov, A.; Jones, J. E.; Xi,
X. X.; Lysczek, E. M.; Redwing, J. M.; Xu, S. Y.; Lettieri, J.;
Schlom, D. G.; Tian, W.; Pan, X. Q.; Liu, Z. K. Nat. Mater. 2002,
1, 35-38. [0207] 8. Fan, Z. Y.; Hinks, D. G.; Newman, N.; Rowell,
J. M. Appl. Phys. Lett. 2001, 79, 87-89. [0208] 9. Becker, W. E.;
Ashby, E. C. Inorg. Chem. 1965, 4, 1816-1818. [0209] 10. Bremer,
M.; Noth, H.; Warchhold, M. Eur. J. Inorg. Chem. 2003, 111-119.
[0210] 11. Lobkovskii, E. B.; Titov, L. V.; Psikha, S. B.; Antipin,
M. Y.; Struchkov, Y. T. J. Struct. Chem. 1982, 23, 644-646. [0211]
12. Noeth, H. Z. Naturforsch. 8 1982, 378, 1499-503. [0212] 13.
Lobkovskii, EB.; Titov, L. V.; Levicheva, M. D.; Chekhlov, A. N. J.
Struct. Chem. 1990, V31, 506-508. [0213] 14. Hermanek, S.; Plesek,
J. Collect. Czech. Chem. Commun. 1966, 31, 177-89. [0214] 15.
Titov, L. V.; Levicheva, M. D.; Psikha, S. B. Zh. Neorg. Khim.
1984, 29, 668-73. [0215] 16. Levicheva, M. D.; Titov, L. V.;
Psikha, S. B. Zh. Neorg. Khim. 1987, 32, 510-12. [0216] 17. Denton,
D. L.; Clayton, W. R.; Mangion, M.; Shore, S. G.; Meyers, E. A.
Inorg. Chem. 1976, 15, 541-548. [0217] 18. Jensen, J. A.; Gozum, J.
E.; Pollina, D. M.; Girolami, G. S. J. Am. Chem. Soc. 1988, 110,
1643-1644. [0218] 19. Goedde, D. M.; Girolami, G. S. J. Am. Chem.
Soc. 2004, 126, 12230-12231. [0219] 20. Jayaraman, S.; Klein, E.
J.; Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson, J. R. J. Vac.
Sci. Technol., A 2005, 23, 631-633. [0220] 21. Sung, J.; Goedde, D.
M.; Girolami, G. S.; Abelson, J. R. J. Appl. Phys. 2002, 91,
3904-3911. [0221] 22. For the details of the growth condition, see:
J., Sreenivas; Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson, J.
R. J. Vac. Sci. Technol., A 2005, 23, 1619-1625. [0222] 23. Gaines,
D. F.; Morris, J. H. J. Chem. Soc., Chem. Commun. 1975, 626-7.
[0223] 24. Lippard, S. J.; Ucko, D. Inorg. Chem. 1968, 7,
1051-1056. [0224] 25. Gaines, D. F.; Hildebrandt, S. J. Inorg.
Chem. 1978, 17, 794-806. [0225] 26. Beckett, M. A.; Brassington, D.
S.; Coles, S. J.; Gelbrich, T.; Hursthouse, M. B. Polyhedron 2003,
22, 1627-1632. [0226] 27. Grebenik, P. D.; Leach, J. B.; Green, M.
L. H.; Walker, N. M. J. Organomet. Chem. 1988, 345, C31-C34. [0227]
28. Calabrese, J. C.; Gaines, D. F.; Hildebrandt, S. J.; Morris, J.
H. J. Am. Chem. Soc. 1976, 98, 5489-5492. [0228] 29. Guggenberger,
L. J. Inorg. Chem. 1970, 9, 367-373. [0229] 30. Bremer, M.; Linti,
G.; Noth, H.; Thomann-Albach, M.; Wagner, G. Z. Anorg. Allg. Chem.
2005, 631, 683-697. [0230] 31. Prust, J.; Most, K.; Muller, I.;
Alexopoulos, E.; Stasch, A.; Uson, I.; Roesky, H. W. Z. Anorg.
Allg. Chem. 2001, 627, 2032-2037. [0231] 32. Hough, W. V.; Edwards,
L. J.; McElroy, A. D. J. Am. Chem. Soc. 1958, 80, 1828-9. [0232]
33. For details of the crystallographic methods used see:
Brumaghim, J. L.; Priepot, J. G.; Girolami, G. S. Organometallics
1999, 18, 2139-2144.
Example 13
Highly Volatile Magnesium Complexes with Diboranamide Ligands.
Synthesis and Characterization of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and Related Compounds
Introduction
[0233] The discovery in 2001 of superconductivity in magnesium
diboride (MgB.sub.2) below 39 K.sup.1 has initiated extensive
research into this material. In addition to possessing the highest
superconducting transition temperature of all intermetallic
superconductors, MgB.sub.2 possesses a long coherence length of ca.
5 nm and a large energy gap,.sup.2-4 which make this material an
attractive replacement for the niobium-based phases currently used
in superconducting circuits. Thin films of MgB.sub.2 are of
particular interest for the fabrication of Josephson junctions, but
a major obstacle is that this phase decomposes with loss of
magnesium above 425.degree. C..sup.5 Overcoming this problem
requires either growing the film below 400.degree. C. or using very
high Mg partial pressures. MgB.sub.2 films have been prepared by
co-evaporation of Mg and B at .about.300.degree. C.,.sup.8 by boron
deposition and subsequent ex-situ annealing under a high Mg
pressure in a sealed tube at 900.degree. C.,.sup.7 and by reaction
of B.sub.2H.sub.6 at 750.degree. C. with Mg vapor that is generated
near the substrate..sup.8 These methods, however, have not yet
proven suitable for the in situ growth of crystalline MgB.sub.2
required for the large scale fabrication of multilayer tunneling
junctions.
[0234] It is known that high-quality thin films of several metal
diboride phases can be grown by chemical vapor deposition (CVD)
from transition metal hydroborates such as
Ti(BH.sub.4).sub.3(dme),.sup.9 Zr(BH.sub.4).sub.4,.sup.10 and
Hf(BH.sub.4).sub.4,.sup.11 and Cr(B.sub.3H.sub.8).sub.2..sup.12,13
As reported herein we synthesized and characterized the new
magnesium compound Mg(B.sub.3H.sub.8).sub.2 and derivatives
thereof, and our initial studies of their use as CVD precursors to
MgB.sub.2 thin films..sup.14 Significantly,
Mg(B.sub.3H.sub.8).sub.2 and its etherates are the only volatile
magnesium hydroborate complexes known; other Mg compounds that
contain tetrahydroborate (BH.sub.4.sup.-),.sup.15-21
octahydrotriborate (B.sub.3H.sub.8.sup.-),.sup.18,22,23 or
nonahydrohexaborate (B.sub.6H.sub.9.sup.-).sup.24 groups are all
non-volatile.
[0235] We now report the synthesis of a new class of remarkably
volatile magnesium complexes of the N,N-dimethyldiboranamide ligand
H.sub.3BNMe.sub.2BH.sub.3.sup.-. Specifically, we describe the
preparation and characterization of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, its adducts with ethers, and
the mixed ligand complex Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf). The
homoleptic complex Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 has a vapor
pressure of 800 mTorr at 25.degree. C., which makes it the most
volatile magnesium complex known.
Results and Discussion
[0236] Synthesis and Characterization of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
[0237] The solid state reaction of MgBr.sub.2 and sodium
N,N-dimethyldiboranamide, Na(H.sub.3BNMe.sub.2BH.sub.3), at room
temperature followed by sublimation at 20-70.degree. C. under a
static vacuum affords a colorless crystalline product,
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, 1, in good yield. This
synthetic method, which involves grinding or milling of the solid
starting materials, avoids the use of solvents such as ethers that
can coordinate to the magnesium center. This air- and
moisture-sensitive magnesium complex sublimes even at room
temperature and has an unusually high vapor pressure of 800 mTorr
at 25.degree. C. It is thermally stable up to 120.degree. C.
MgBr.sub.2+2Na(H.sub.3BNMe.sub.2BH.sub.3).sub.2-.fwdarw.Mg(H.sub.3BNMe.s-
ub.2BH.sub.3).sub.2+2NaBr (1)
[0238] The infrared spectrum of 1 features a strong band at 2449
cm.sup.-1 due to terminal B-H stretches, and a strong, broad band
centered at 2195 cm.sup.-1 due to bridging B-H stretches. These B-H
stretching bands are similar to those observed in the IR spectra of
transition metal complexes of the diboranamide ligand..sup.25
[0239] The .sup.1H NMR spectrum of 1 at 20.degree. C. shows two
signals, a singlet at .delta. 2.04 for the NMe.sub.2 groups and a
broad 1:1:1:1 quartet at .delta. 1.91 for the BH.sub.3 groups
(.sup.11B has I=3/2) The J.sub.BH coupling constant of 90.0 Hz is
nearly identical to the 91 and 92 Hz values observed for the thf
and 15-crown-5 solvates of Na(H.sub.3BNMe.sub.2BH.sub.3),.sup.26
respectively, and slightly larger than the 74-83 Hz range found in
magnesium tetrahydroborates.sup.17,20 At -80.degree. C., the
quartet becomes a broad unresolved signal due to the more rapid
spin-lattice relaxation of the .sup.11B and .sup.10B nuclei at a
lower temperature, as seen in many transition metal
tetrahydroborates..sup.27,28 Exchange of terminal B-H hydrogen
atoms with those that bridge to the metal center (see structure
below) is evidently fast on the NMR time scale even at -80.degree.
C.
[0240] Crystal Structure of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
[0241] The molecular structure of 1 is presented in FIG. 8;
crystallographic data and selected bond distances and angles are
listed in Tables 1 and 2. The magnesium center is coordinated to
two chelating [H.sub.3BNMe.sub.2BH.sub.3].sup.- ligands, which are
similar but crystallographically inequivalent. The planes of the
two ligands (as defined by the B-N-B backbones) are related by a
dihedral angle of 46.7(1).degree.. If each BH.sub.3 unit is
considered to occupy one coordination site, the overall geometry
about the magnesium center is nearly exactly halfway between square
planar (dihedral angle of 0.degree.) and tetrahedral (dihedral
angle of 90.degree.). The factors that favor the adoption of this
unusual coordination geometry are not immediately obvious, and may
be the result of packing forces. A similar dihedral angle of
46.5(2).degree. has been found for the high-spin d.sup.5 manganese
analogue Mn(H.sub.3BNMe.sub.2BH.sub.3).sub.2..sup.25
[0242] Two hydrogen atoms from each BH.sub.3 group bridge to the
magnesium center to form total eight Mg-H contacts; the Mg-H bond
lengths are essentially identical and average 2.02(3) .ANG.. The
average B-H distances of 1.14(3) .ANG. within the Mg-H-B bridges is
slightly longer than the average terminal B-H distance of 1.05(2)
.ANG., as expected. The dihedral angle between the two
Mg(.mu.-H).sub.2 planes at each end of a dimethyldiboranamide
ligand is 93.8.degree., whereas the average B-Mg-B angle within a
diboranamide ligand is 66.0(6).degree.. The Mg . . . B distances
are almost equal at 2.369(1) and 2.386(1) .ANG., and the B-N
distances are identical within experimental error at 1.585(1) and
1.581(1) .ANG.. The geometry about the nitrogen atoms is nearly
perfect tetrahedron: the B-N-B, B-N-C, and C-N-C angles of
108.5(1)-110.2(1).degree. are all within about 1.degree. of the
ideal value 109.5.degree..
[0243] The Mg-H and Mg . . . B distances in
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 can be profitably compared with
those of magnesium complexes containing bidentate BH.sub.4.sup.-
ligands, which are electronically and structurally similar. The
Mg-H distance of 2.02(3) .ANG. in 1 falls in the 1.97-2.09 .ANG.
range observed in magnesium complexes containing bidentate BH.sub.4
groups..sup.15-17,19-21 In contrast, the Mg . . . B distances of
2.369(1) and 2.386(1) .ANG. in 1 are shorter than those of
2.40-2.54 .ANG. seen for magnesium complexes of bidentate BH.sub.4
ligands..sup.17,19-21 This shorter Mg . . . B distance of 1 is a
consequence of the chelating nature of the dimethyldiboranamide
ligand, which causes the Mg(.mu.-H).sub.2B units to be non-planar,
i.e, folded about the H . . . H axis; in contrast, in Mg-BH.sub.4
complexes the Mg(.mu.-H).sub.2B units are planar, thus maximizing
the Mg . . . B distance.
[0244] Volatility of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
[0245] The 800 mTorr vapor pressure of 1 at 25.degree. C. is
remarkably high for a magnesium compound, which in part reflects
its low molecular weight. It can be sublimed in vacuum at
reasonable rates even at room temperature. This volatility makes 1
an attractive chemical vapor deposition (CVD) precursor for
magnesium-containing phases, as is described herein. In comparison,
all other magnesium compounds have lower volatilities. The widely
used CVD source dicyclopentadienylmagnesium (Cp.sub.2Mg) has a
vapor pressure described by the equation logP (in
Torr)=10.452-3522/T (in Kelvin), which corresponds to .about.45
mTorr at 25.degree. C..sup.29 The magnesium amidinate complexes
bis(N,N'-di-tert-butylacetamidinato)magnesium and
bis(N,N'-diisopropylacetamidinato)magnesium sublime readily only
when heated under vacuum to 70.degree. C.; although they have been
reported to be more volatile than Cp.sub.2Mg on the basis of their
sublimation temperatures in the same evaporation apparatus, the
vapor pressures have not been reported..sup.30 The volatilities of
these amidinate complexes are limited by the need to prevent
oligomerization by attaching bulky substituents to the amidinate
backbone, thus increasing the molecular weight. Magnesium
2,2,6,6-tetramethyl-3,5-heptanedionate (thd), which is a dimer,
Mg.sub.2(thd).sub.4,.sup.31 has been used as a CVD or atomic layer
deposition (ALD) precursor for MgO thin films..sup.31-34 This
compound evaporates at reasonable rates only above 250.degree. C.,
as determined by thermogravimetric analyses under a helium
flow..sup.31,35 Monomeric Mg(thd).sub.2L.sub.x complexes can be
made with a variety of Lewis bases, but their volatilities are only
slightly higher than that of Mg.sub.2(thd).sub.4..sup.36,37
Magnesium complexes of the fluorinated .beta.-diketonate ligand,
1,1,1,5,5,5-hexafluoro-2,4-pentanedionate (hfa), especially those
carrying ancillary diamine ligands, are more volatile than
Mg.sub.2(thd).sub.4 and its related complexes; however, even the
most volatile of these complexes,
Mg(hfa)(Me.sub.2NCH.sub.2CH.sub.2NMe.sub.2), evaporates readily
only at .about.100.degree. C. under 5 Torr of nitrogen..sup.38
Finally, the heteroleptic 13-diketiminato magnesium complex
(cyclopentadienyl)(N,N'-di-tert-butyl-2,4-pentanediketiminato)magnesium
is nearly as volatile as Cp.sub.2Mg, and the binary
.beta.-diketiminato magnesium complexes
bis(N,N'-di-tert-butyl-2,4-pentanediketiminato)magnesium and
bis(N,N'-diisopropyl-2,4-pentanediketiminato)magnesium sublime at
104 and 160.degree. C., respectively, at 0.05 Torr..sup.39
[0246] Synthesis and Characterization of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf) and
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme).
[0247] Treatment of MgBr.sub.2 with Na(H.sub.3BNMe.sub.2BH.sub.3)
in tetrahydrofuran, followed by sublimation at 70.degree. C.,
affords white crystals of the thf adduct
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf), 2. Carrying out this
reaction in 1,2-dimethoxyethane affords the related compound
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme), 3.
MgBr.sub.2+2Na(H.sub.3BNMe.sub.2BH.sub.3).sub.2+L-.fwdarw.Mg(H.sub.3BNMe-
.sub.2BH.sub.3).sub.2(L)+2NaBr [0248] (2) L=thf [0249] (3)
L=dme
[0250] The infrared spectrum of 2 contains three strong bands in
the B-H stretch region: a strong terminal B-H stretch at 2391
cm.sup.-1, and two strong bridging B-H stretches at 2300 and 2241
cm.sup.-1. Very similar bands are seen for 3. Relative to the
features seen for unsolvated 1, the terminal B-H stretch appears at
a lower frequency (and thus largely overlaps with the bridging B-H
stretches), whereas the bridging B-H stretches appear at higher
frequencies. These differences suggest that the Mg-diboranamide
interaction is weaker in the ether adducts, a conclusion that is
consistent with the longer Mg-H and Mg . . . B bonds seen in their
crystal structures (see below). The .sup.1H NMR spectrum of 2 at
20.degree. C. shows a broad quartet at .delta. 1.99 for the
BH.sub.3 groups, and a similar feature at .delta. 2.11 is seen for
1.
[0251] Crystal Structures of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf) and
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme).
[0252] The molecular structure of 2 and 3 are presented in FIGS. 9
and 10; crystallographic data, and selected bond distances and
angles are listed in Tables 1, 3, and 4. For the thf adduct 2, the
magnesium center adopts a distorted square pyramidal geometry in
which four BH.sub.3 groups from two chelating diboranamide ligands
occupy basal positions and the thf molecule occupies the apical
site. Each BH.sub.3 group of the diboranamide ligand coordinates to
the magnesium center in a bidentate mode like that seen in 1, but
the Mg-H distances of 2.13(10) .ANG. are longer by about 0.1 .ANG.
than those in 1. Similarly, the Mg . . . B distances of
2.484(4)-2.553(5) .ANG. are 0.1-0.15 .ANG. longer than those in 1.
These longer Mg-H and Mg . . . B distances, which suggest a weaker
Mg-diboranamide interaction, reflect the higher degree of steric
crowding in 2 due to the presence of the additional tetrahydrofuran
ligand. In 2, the B-H distances to the bridging hydrogen atoms of
1.11 .ANG. and those to the terminal hydrogen atoms of 1.10 .ANG.
are essentially identical. This pattern differs from that in
unsolvated 1, in which the bridging B-H distances were longer by
nearly 0.1 .ANG., which again suggests that the Mg-diboranamide
bonding is weaker in the ether adduct than in 1. The average B-Mg-B
angle of 60.7.degree. is some 6.degree. smaller than that in 1
owing to the longer M-B distances in 2.
[0253] The magnesium center in the dme adduct 3 adopts a distorted
octahedral geometry in which two diboranamide groups and one dme
group act as chelating ligands. Unlike 1 and 2, in which eight
hydrogen atoms form close contacts with the Mg atom, in 3 only five
hydrogen atoms (H11, H21, H31, H41, and H42) form short Mg-H-B
bridges, which range from 1.98(1) to 2.20(1) .ANG.. The next
shortest Mg-H contacts of 2.43(1) and 2.39(1) .ANG. are formed to
H12 and H32, respectively; all the other Mg-H distances are greater
than 3 .ANG.. The Mg . . . B distances of 2.608(2)-2.868(2) .ANG.
are also considerably longer than those in 2 by .about.0.4 .ANG..
The large Mg-H and Mg . . . B distances are consistent with the
higher degree of steric congestion caused by the bidentate dme
ligand. The long M . . . B distances in 3 cause the B-Mg-B angles
of 56.11(5) and 59.36(5).degree. within each diboranamide ligand to
be smaller than those in 1 and 2.
[0254] Synthesis and Characterization of
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf).
[0255] Treatment of the magnesium pentamethylcyclopentadienyl
complex [Cp*MgCl(thf)].sub.2 with one equivalent of
Na(H.sub.3BNMe.sub.2BH.sub.3) in diethyl ether affords the
diboranamide complex Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf), 4,
which can be obtained as white crystals by sublimation at
60.degree. C. and 0.05 Torr.
1/2[Cp*MgCl(thf)].sub.2+Na(H.sub.3BNMe.sub.2BH.sub.3).sub.2-.fwdarw.Cp*M-
g(H.sub.3BNMe.sub.2BH.sub.3)(thf)+NaCl (4)
[0256] The B-H stretching modes in the IR spectrum of 4 closely
resemble those seen for 2 and 3: there is a strong terminal B-H
stretching band at 2393 cm.sup.-1 and three strong bridging B-H
stretching bands at 2297, 2241, and 2185 cm.sup.-1. The .sup.1H NMR
spectrum of 4 at 20.degree. C. contains a broad singlet at .delta.
2.21 for the BH.sub.3 groups, a singlet at .delta. 2.14 for Cp*
ring, and a singlet at .delta. 1.94 for NMe.sub.2 groups, and
characteristic resonances for the thf protons. Interestingly, based
on the solid state structure (see below) there should be two
NMe.sub.2 environments: one methyl group should be proximal to the
Cp* group and the other should be distal. Evidently, there is some
exchange process that renders these two groups equivalent; there is
also only one signal for the NMe.sub.2 group in the .sup.13C NMR
spectrum.
[0257] Crystal Structure of
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf).
[0258] The molecular structure of 4 is shown in FIG. 11;
crystallographic data and selected bond distances and angles are
listed in Tables 1 and 5. The magnesium center is coordinated to
one .eta..sup.5-Cp* ligand, one chelating
[H.sub.3BNMe.sub.2BH.sub.3].sup.- ligand, and one thf molecule. All
the BH.sub.3 groups are bound to the magnesium center by means of
two bridging hydrogen atoms. Three of Mg-H distances are equal,
averaging 2.22(8) .ANG., and one may be slightly longer at 2.30(4)
.ANG.. The Mg . . . B distances are nearly identical at 2.534(7)
and 2.554(8) .ANG.. Although of marginal significance
statistically, the refined B-H distances to the hydrogens that are
proximal to the Cp* ring (1.22(4) and 1.18(4) .ANG.) are slightly
longer than those to hydrogens that are distal (1.15(3) and 1.15(4)
.ANG.). The terminal B-H distances are 1.15(3) and 1.07(4) .ANG..
The Mg-C distances fall in a narrow range 2.360(5)-2.414(6) .ANG.;
the average Mg-C distance of 2.38(1) .ANG. is similar to that of
2.38(2) A seen in [Cp*MgCl(thf)].sub.2.sup.40 but shorter than that
of 2.44(3) .ANG. seen in CpMg(.eta..sup.2-t-BuC(NMes).sub.2)(thf),
where Mes=2,4,6- C.sub.6H.sub.2Me.sub.3..sup.41
Experimental Section
[0259] All experiments were carried out under vacuum or under argon
by using standard Schlenk techniques. Solvents were distilled under
nitrogen from sodium/benzophenone immediately before use. The
starting materials Na(H.sub.3BNMe.sub.2BH.sub.3),.sup.26 and
Cp*MgCl(thf).sup.42 were prepared by literature procedures.
MgBr.sub.2 was used as received from Aldrich. Microanalyses were
performed by the University of Illinois Microanalytical Laboratory.
The IR spectra were recorded on a Nicolet Impact 410 instrument as
Nujol mulls between KBr plates. The .sup.1H and .sup.13C NMR data
were collected on a Varian Gemini 500 instrument at 499.699 MHz and
125.663 MHz, respectively. Chemical shifts are reported in 6 units
(positive shifts to high frequency) relative to tetramethylsilane.
Field ionization (FI) mass spectra were recorded on a Micromass
70-VSE mass spectrometer. The shapes of all peak envelops
correspond with those calculated from the natural abundance
isotopic distributions. Melting points and decomposition
temperatures were determined in closed capillaries under argon on a
Thomas-Hoover Unimelt apparatus. Vapor pressures were measured by
placing samples in a closed vessel equipped with a MKS 627B
absolute capacitance manometer. The pressure increase as a function
of time was plotted, and the vapor pressure determined from the
y-axis intercept obtained by extrapolating the linear portion of
the curve at longer times back to t=0.
[0260] Bis(N,N-dimethyldiboranamido)magnesium,
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, 1.
[0261] Solid MgBr.sub.2 (1.94 g, 10.5 mmol) and
Na(H.sub.3BNMe.sub.2BH.sub.3) (2.0 g, 21.0 mmol) were ground
together briefly in a mortar and pestle. The dry solid mixture was
transferred to a 100 mL round-bottom Schlenk flask, and 30-40 steel
balls (4.5-mm diameter) were added. The flask was gently agitated
for 30 min. Sublimation at 70.degree. C. under static vacuum
afforded white crystals (under a dynamic vacuum, substantial amount
of the product can be lost). Yield: 1.13 g (64%). Vapor pressure at
25.degree. C.: 0.8.+-.0.1 torr. Mp: 70.degree. C. .sup.1H NMR
(C.sub.7D.sub.8, 20.degree. C.): .delta. 2.04 (s, 12H, NMe.sub.2),
1.91 (q, J.sub.BH=90.0 Hz, 12H, BH.sub.3). .sup.13C{.sup.1H} NMR
(C.sub.7D.sub.8, 20.degree. C.): .delta. 50.98 (s, NMe.sub.2).
Anal. Calcd for C.sub.4H.sub.24N.sub.2B.sub.4Mg: C, 28.6; H, 14.4;
N, 16.6; B, 25.8; Mg, 14.5. Found: C, 28.6; H, 15.1; N, 16.6, B,
25.7; Mg, 14.1. IR (cm.sup.-1): 2449 s, 2355 w, 2294 w, 2195 s,
2149 m, 2078 w, 1312 s, 1239 m, 1219 m, 1178 s, 1142 s, 1022 s, 927
m, 904 m, 810 m, 521 s, 421 s.
[0262] Bis(N,N-dimethyldiboranamido)(tetrahydrofuran)magnesium,
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf), 2.
[0263] To a suspension of MgBr.sub.2 (0.51 g, 2.8 mmol) in
tetrahydrofuran (20 mL) at room temperature was added a solution of
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.53 g, 5.6 mmol) in tetrahydrofuran
(30 mL). After the reaction mixture had been stirred for 8 h at
room temperature, the solvent was removed in vacuum. Sublimation at
70.degree. C. and at 0.05 Torr afforded white crystals. Yield: 0.31
g (47%). .sup.1H NMR (C.sub.7D.sub.8, 20.degree. C.): .delta. 3.57
(m, 4H, OCH.sub.2), 2.33 (s, 12H, NMe.sub.2), 1.99 (q,
J.sub.BH=84.5 Hz, 12H, BH.sub.3), 1.28 (m, 4H, OCH.sub.2CH.sub.2).
.sup.13C{.sup.1H} NMR (C.sub.7D.sub.8, 20.degree. C.): .delta. 69.2
(s, OCH.sub.2), 52.4 (s, NCH.sub.3), 25.5 (s, OCH.sub.2CH.sub.2).
Anal. Calcd for C.sub.8H.sub.32N.sub.2B.sub.40 Mg: C, 40.1; H,
13.4; N, 11.7; B, 18.0; Mg, 10.1. Found: C, 39.5; H, 13.3; N, 11.3;
B, 16.0; Mg, 10.5. IR (cm.sup.-1): 2391 s, 2300 s, 2241 s, 2975 w,
1298 m, 1237 m, 1216 m, 1177 s, 1148 s, 1023 s, 929 m, 873 s, 816
m, 693 w.
[0264] Bis(N,N-dimethyldiboranamido)(dimethoxyethane)magnesium,
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme), 3
[0265] To a suspension of MgBr.sub.2 (0.51 g, 2.8 mmol) in
1,2-dimethoxyethane (20 mL) at room temperature was added a
solution of Na(H.sub.3BNMe.sub.2BH.sub.3) (0.53 g, 5.6 mmol) in
1,2-dimethoxyethane (30 mL). After the reaction mixture had been
stirred for 8 h at room temperature, the solvent was removed in
vacuum. Sublimation at 70.degree. C. and at 0.05 Torr afforded
white crystals. Yield: 0.27 g (37%). .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 3.00 (s, 6H, OMe), 2.81 (s, 4H, OCH.sub.2),
2.48 (s, 12H, NMe.sub.2), 2.11 (q, J.sub.BH=88.5 Hz, 12H,
BH.sub.3). .sup.13C{.sup.1H} NMR (C.sub.6D.sub.6, 20.degree. C.):
.delta. 69.6 (s, OCH.sub.2), 59.6 (s, OCH.sub.3), 52.6 (s,
NMe.sub.2). Anal. Calcd for C.sub.8H.sub.34N.sub.2B.sub.4O.sub.2Mg:
C, 37.3; H, 13.3; N, 10.9; B, 16.8; Mg, 9.42. Found: C, 36.4; H,
13.2; N, 10.4; B, 17.1; Mg, 9.92. IR (cm.sup.-1): 2411 w, 2357 s,
2290 s, 2230 s, 2066 w, 1299 w, 1276 w, 1236 w, 1212 w, 1176 s,
1148 s, 1094m, 1054 s, 1018 s, 925 w, 871 m, 811 w.
[0266]
(Pentamethylcyclopentadienyl)(N,N-dimethyldiboranamido)(tetrahydrof-
uran)magnesium(II), Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf), 4
[0267] To a suspension of Cp*MgCl.thf (0.99 g, 3.7 mmol) in
Et.sub.2O (25 mL) at -78.degree. C. was added a solution of
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.38 g, 4.0 mmol) in Et.sub.2O (20
mL). The reaction mixture was stirred for 10 min, allowed to warm
to room temperature, and stirred for 5 h to give a colorless
solution and a white precipitate. The solution was filtered and the
filtrate was taken to dryness in vacuum. Sublimation at 60.degree.
C. and at 0.05 Torr in vacuum yielded white crystals. Yield: 0.68 g
(63%). .sup.1H NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 3.42
(m, 4H, OCH.sub.2), 2.21 (br, 6H, BH.sub.3), 2.14 (s, 15H,
C.sub.5Me.sub.5), 1.94 (s, NMe.sub.2), 1.17 (m, 4H,
OCH.sub.2CH.sub.2). .sup.13C{.sup.1H} NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 110.40 (s, C.sub.5Me.sub.5), 69.55 (s,
OCH.sub.2), 52.45 (s, NMe.sub.2), 25.32 (s, OCH.sub.2CH.sub.2),
11.16 (s, C.sub.5Me.sub.5). Anal. Calcd for
C.sub.16H.sub.35NB.sub.4OMg: C, 63.3; H, 11.6; N, 4.62; B, 7.13;
Mg, 8.01. Found: C, 62.1; H, 11.7; N, 5.11; B, 9.20; Mg, 8.24. IR
(cm.sup.-1): 2434 sh, 2393 s, 2297 s, 2241 s, 2185 s, 2077 m, 1342
w, 1311 w, 1294 w, 1277 w, 1238 w, 1213 w, 1176 s, 1146 s, 1024 s,
926 m, 910 m, 874 s, 806 m, 681 w.
[0268] X-Ray Structure Determinations..sup.43
[0269] Single crystals of all four compounds, grown by sublimation,
were mounted on glass fibers with Krytox oil (DuPont), and
immediately cooled to -80.degree. C. in a cold nitrogen gas stream
on the diffractometer. Data for 1-4 were collected with an area
detector by using the measurement parameters listed in Table 1. The
measured intensities were reduced to structure factor amplitudes
and their esd's by correction for background, and Lorentz and
polarization effects. Systematically absent reflections were
deleted and symmetry-equivalent reflections were averaged to yield
the sets of unique data. The analytical approximations to the
scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. All structures were solved using direct methods
(SHELXTL). The correct positions for all non-hydrogen atoms of 1-4
were deduced from E-maps. Final refinement parameters for 1-4 are
given in Table 1. A final analysis of variance between observed and
calculated structure factors showed no apparent errors. Subsequent
discussions for 1-4 will be divided into individual paragraphs.
[0270] Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, 1.
[0271] Systematic absences for hkl (h+k+l.noteq.2n), and hhl
(2h+l.noteq.4n) were consistent with space groups l 42d and
l4.sub.1md; the group l 42d was shown to be the correct choice by
successful refinement of the proposed model. All 1542 unique
reflections were used in the least squares refinement. Although
corrections for crystal decay were unnecessary, a face-indexed
absorption correction was applied. The quantity minimized by the
least-squares program was .SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2),
where w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0449P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. The locations of the hydrogen
atoms were refined without constraints and each was given an
independent anisotropic displacement parameter. An isotropic
extinction parameter was refined to a final value of
x=2.7(2).times.10.sup.-5 where F.sub.c is multiplied by the factor
k[1+F.sub.c.sup.2.times..lamda..sup.3/sin 2.theta.].sup.-1/4 with k
being the overall scale factor. Successful convergence was
indicated by the maximum shift/error of 0.001 for the last cycle.
Final refinement parameters are given in Table 1. The largest peak
in the final Fourier difference map (0.12 e.ANG..sup.-3) was
located 1.27 .ANG. from H(21).
[0272] Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(thf), 2.
[0273] Systematic absences for hkl (h+k.noteq.2n) and
h0l(l.noteq.2n) were consistent with space groups Cc and C2/c; the
non-centrosymmetric Cc was shown to be the correct choice by
successful refinement of the proposed model. All 2576 unique
reflections were used in the least squares refinement. Although
corrections for crystal decay were unnecessary, a face-indexed
absorption correction was applied. The quantity minimized by the
least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0735P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. The B-H distances involving the
bridging hydrogen atoms were constrained to equal within 0.05
.ANG.; similar constraints were applied for chemically related B-H
distances to the terminal hydrogen atoms. Methyl hydrogen atoms
were placed in idealized locations with C-H=0.98 .ANG. and were
assigned displacement parameters equal to 1.5 times U.sub.eq for
the attached carbon atom; the methyl groups were allowed to rotate
about the N-C axis to find the best least-squares positions.
Methylene hydrogen atoms were also placed in idealized locations
with C-H=0.99 .ANG. and their displacement parameters were set
equal to 1.2 times U.sub.eq for the attached carbon atom. The
displacement parameter for B2 was suspiciously large and probably
reflects disorder in this site. Successful convergence was
indicated by the maximum shift/error of 0.001 for the last cycle.
Final refinement parameters are given in Table 1. The largest peak
in the final Fourier difference map (0.18 e.ANG..sup.-3) was
located 0.97 .ANG. from B(2).
[0274] Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2(dme), 3.
[0275] Systematic absences for hkl (h+k.noteq.2n) and h0l
(l.noteq.2n) were consistent with space groups Cc and C2/c; the
centrosymmetric group C2/c was shown to be the correct choice by
successful refinement of the proposed model. All 3840 unique
reflections were used in the least squares refinement. Although
corrections for crystal decay were unnecessary, a face-indexed
absorption correction was applied. The quantity minimized by the
least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0473P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. Hydrogen atoms surfaced in the
difference maps and their locations were refined without
constraints. Hydrogen atoms attached to boron were each given an
independent isotropic displacement parameter; methyl and methylene
hydrogens were assigned isotropic displacement parameters equal to
1.5 times U.sub.eq and 1.2 times U.sub.eq for the attached carbon
atom, respectively. Successful convergence was indicated by the
maximum shift/error of 0.001 for the last cycle. Final refinement
parameters are given in Table 1. The largest peak in the final
Fourier difference map (0.18 e.ANG..sup.-3) was located 0.82 .ANG.
from B(3).
[0276] Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf), 4.
[0277] Systematic absences for 0k0 (k.noteq.2n) and h0l
(h+l.noteq.2n) were only consistent with space group P2.sub.1ln.
All 3827 unique data were used in the least squares refinement.
Although corrections for crystal decay were unnecessary, a
face-indexed empirical absorption correction was applied. The
quantity minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.04P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. Late in the refinement, it
became clear that the data crystal was twinned by merohedry; the
twin law corresponds to reflection through the be plane (or
180.degree. rotation about c). The calculated intensities were set
equal to the formula l.sub.calc=xl.sub.hkl+(1-x)l.sub.h'k',l',
where h'=-h, k'=k, and l'=l, and x is the volume fraction of the
major twin individual. The value of x refined to 0.868(2). In the
final cycle of least squares, independent anisotropic displacement
factors were refined for the non-hydrogen atoms. The locations of
the hydrogen atoms attached to boron were refined without
constraints; these hydrogen atoms were each given independent
isotropic displacement parameters. Hydrogen atoms attached to
carbon were placed in idealized positions with C-H=0.98 .ANG. for
methyl hydrogens and 0.99 .ANG. for methylene hydrogens; the methyl
groups were allowed to rotate about the C-C axis to find the best
least-squares positions. The displacement parameters for methyl
hydrogens were set to 1.5 times U.sub.eq for the attached carbon;
those for methylene hydrogens were set equal to 1.2 times U.sub.eq.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. Final refinement parameters are given in
Table 1. The largest peak in the final Fourier difference map (0.17
e.ANG..sup.-3) was located 0.64 .ANG. from carbon atom C(6).
REFERENCES
[0278] 1. Nagamatsu, J.; Nakagawa, N.; Muranaka, T.; Zenitani, Y.;
Akimitsu, J. Nature 2001, 410, 63-64. [0279] 2. Xu, M.; Kitazawa,
H.; Takano, Y.; Ye, J.; Nishida, K.; Abe, H.; Matsushita, A.;
Tsujii, N.; Kido, G. Appl. Phys. Lett. 2001, 79, 2779-2781. [0280]
3. Schmidt, H.; Zasadzinski, J. F.; Gray, K. E.; Hinks, D. G. Phys.
Rev. Lett. 2002, 88. [0281] 4. Tsuda, S.; Yokoya, T.; Kiss, T.;
Takano, Y.; Togano, K.; Kito, H.; Ihara, H.; Shin, S. Phys. Rev.
Lett. 2001, 8717. [0282] 5. Fan, Z. Y.; Hinks, D. G.; Newman, N.;
Rowell, J. M. Appl. Phys. Lett. 2001, 79, 87-89. [0283] 6. Ueda,
K.; Naito, M. J. Appl. Phys. 2003, 93, 2113-2120. [0284] 7. Kang,
W. N.; Kim, H. J.; Choi, E. M.; Jung, C. U.; Lee, S. L. Science
2001, 292, 1521-1523. [0285] 8. Zeng, X. H.; Pogrebnyakov, A. V.;
Kotcharov, A.; Jones, J. E.; Xi, X. X.; Lysczek, E. M.; Redwing, J.
M.; Xu, S. Y.; Lettieri, J.; Schlom, D. G.; Tian, W.; Pan, X. Q.;
Liu, Z. K. Nat. Mater. 2002, 1, 35-38. [0286] 9. Jensen, J. A.;
Gozum, J. E.; Pollina, D. M.; Girolami, G. S. J. Am. Chem. Soc.
1988, 110, 1643-1644. [0287] 10. Sung, J.; Goedde, D. M.; Girolami,
G. S.; Abelson, J. R. J. Appl. Phys. 2002, 91, 3904-3911. [0288]
11. Jayaraman, S.; Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson,
J. R. J. Vac. Sci. Technol., A 2005, 23, 1619-1625. [0289] 12.
Goedde, D. M.; Girolami, G. S. J. Am. Chem. Soc. 2004, 126,
12230-12231. [0290] 13. Jayaraman, S.; Klein, E. J.; Yang, Y.; Kim,
D. Y.; Girolami, G. S.; Abelson, J. R. J. Vac. Sci. Technol., A
2005, 23, 631-633. [0291] 14. See Example 12. [0292] 15. Bremer,
M.; Linti, G.; Noth, H.; Thomann-Albach, M.; Wagner, G. Z. Anorg.
Allg. Chem. 2005, 631, 683-697. [0293] 16. Prust, J.; Most, K.;
Muller, I.; Alexopoulos, E.; Stasch, A.; Uson, I.; Roesky, H. W. Z.
Anorg. Allg. Chem. 2001, 627, 2032-2037. [0294] 17. Bremer, M.;
Noth, H.; Warchhold, M. Eur. J. Inorg. Chem. 2003, 111-119. [0295]
18. Hermanek, S.; Plesek, J. Collect. Czech. Chem. Commun. 1966,
31, 177-89. [0296] 19. Lobkovskii, E. B.; Titov, L. V.; Psikha, S.
B.; Antipin, M. Y.; Struchkov, Y. T. J. Struct. Chem. 1982, 23,
644-646. [0297] 20. Noeth, H. Z. Naturforsch. 8 1982, 378,
1499-503. [0298] 21. Lobkovskii, E. B.; Titov, L. V.; Levicheva, M.
D.; Chekhlov, A. N. J. Struct. Chem. 1990, V31, 506-508. [0299] 22.
Levicheva, M. D.; Titov, L. V.; Psikha, S. B. Zh. Neorg. Khim.
1987, 32, 510-12. [0300] 23. Titov, L. V.; Levicheva, M. D.;
Psikha, S. B. Zh. Neorg. Khim. 1984, 29, 668-73. [0301] 24. Denton,
D. L.; Clayton, W. R.; Mangion, M.; Shore, S. G.; Meyers, E. A.
Inorg. Chem. 1976, 15, 541-548. [0302] 25. See Example 12. [0303]
26. Noth, H.; Thomas, S. Eur. J. Inorg. Chem. 1999, 1373-1379.
[0304] 27. Marks, T. J.; Kolb, J. R. Chem. Rev. 1977, 77, 263-93.
[0305] 28. Marks, T. J.; Shimp, L. A. J. Am. Chem. Soc. 1972, 94,
1542-1550. [0306] 29. Product data sheet for Cp.sub.2Mg (Rohm and
Hass Electronic Materials, 2007). [0307] 30. Sadique, A. R.; Heeg,
M. J.; Winter, C. H. Inorg. Chem. 2001, 40, 6349-6355. [0308] 31.
Hatanpaa, T.; Ihanus, J.; Kansikas, J.; Mutikainen, I.; Ritala, M.;
Leskela, M. Chem. Mater. 1999, 11, 1846-1852. [0309] 32. Kwak, B.
S.; Boyd, E. P.; Zhang, K.; Erbil, A.; Wilkins, B. Appl. Phys.
Lett. 1989, 54, 2542-2544. [0310] 33. Zhao, Y. W.; Suhr, H. Appl.
Phys. A: Mater. Sci. Process. 1992, 54, 451-454. [0311] 34. Lu, Z.;
Feigelson, R. S.; Route, R. K.; Dicarolis, S. A.; Hiskes, R.;
Jacowitz, R. D. J. Cryst. Growth 1993, 128, 788-792. [0312] 35.
Schwarberg, J. E.; Sievers, R. E.; Moshier, R. W. Anal. Chem. 1970,
42, 1828-1830. [0313] 36. Hatanpaa, T.; Kansikas, J.; Mutikainen,
I.; Leskela, M. Inorg. Chem. 2001, 40, 788-794. [0314] 37. Babcock,
J. R.; Wang, A. C.; Metz, A. W.; Edleman, N. L.; Metz, M. V.; Lane,
M. A.; Kannewurf, C. R.; Marks, T. J. Chem. Vap. Deposition 2001,
7, 239-+. [0315] 38. Wang, L.; Yang, Y.; Ni, J.; Stern, C. L.;
Marks, T. J. Chem. Mater. 2005, 17, 5697-5704. [0316] 39.
El-Kaderi, H. M.; Xia, A. B.; Heeg, M. J.; Winter, C. H.
Organometallics 2004, 23, 3488-3495. [0317] 40. Cramer, R. E.;
Richmann, P. N.; Gilje, J. W. J. Organomet. Chem. 1991, 408,
131-136. [0318] 41. Xia, A.; El-Kaderi, H. M.; Jane Heeg, M.;
Winter, C. H. J. Organomet. Chem. 2003, 682, 224-232. [0319] 42.
Fagan, P. J.; Manriquez, J. M.; Maatta, E. A.; Seyam, A. M.; Marks,
T. J. J. Am. Chem. Soc. 1981, 103, 6650-6667. [0320] 43. For
details of the crystallographic methods used see: Brumaghim, J. L.;
Priepot, J. G.; Girolami, G. S. Organometallics 1999, 18,
2139-2144.
Example 14
Volatile Lanthanide Complexes with Diboranamide Ligands. Synthesis
and Characterization of Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6,
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, and their Adducts with
Tetrahydrofuran
Introduction
[0321] Of the known metal boride phases, some of the most
interesting are the rare earth metal hexaborides (LnB.sub.6,
Ln=lanthanide elements, including yttrium). These materials have
remarkable structures, in which B.sub.6 octahedra are linked to one
another through their corners by exo B-B bonds to form a Cartesian
lattice. The metal atoms are located at the centers of the holes
formed by this lattice; they are surrounded by the triangular faces
of eight adjacent B.sub.6 octahedra, and so have 24 boron atoms as
nearest neighbors. The physical properties of metal hexaborides are
also of interest: these materials have been used as electron
emitters in instruments such as scanning and transmission electron
microscopes..sup.1-6
[0322] The low work functions, low vapor pressures at elevated
temperatures, and high mechanical strengths.sup.7-9 make LnB.sub.6
phases excellent materials for these applications, which involve
strong electric fields, extremely high vacuum, high temperatures,
and the presence of highly-reactive ionized gases. Because
LnB.sub.6 phases are highly absorbing in the near infrared region,
but have high transmittance and low reflectance in the visible
region, they are also excellent solar radiation shielding
materials..sup.10
[0323] Generation of a strong local electric field is crucial for
efficient field emission, and so electron emitters in electron
microscopes are best formed into shapes with high
curvature..sup.11-14 Typically, single crystals of LnB.sub.6 are
employed, but an alternative approach uses physical vapor
deposition (PVD) to grow a LnB.sub.6 film onto a sharp tungsten,
molybdenum, or silicon tip..sup.15-20 Further improvements may be
possible by taking advantage of the very sharp tips of
nano-materials. For example, Zhang et al. have demonstrated that
nanowires of LaB.sub.6, CeB.sub.6, and GdB.sub.6 can be grown by
CVD..sup.21-24 A drawback of current CVD routes to thin films of
LnB.sub.6--i.e., the reduction of LnCl.sub.3 and BCl.sub.3 by
H.sub.2-- is that they require high-temperatures (800-1500.degree.
C.)..sup.21-26 Single source CVD routes, which often work well at
much lower temperatures, have not been developed. Of the few known
compounds that contain both lanthanide and boron--most of which are
lanthanide tetrahydroborate complexes such as
Ln(BH.sub.4).sub.3(thf).sub.n, Ln(BH.sub.4).sub.2L.sub.2,
Cp.sub.2Ln(BH.sub.4)(thf), and
(C.sub.5H.sub.4CH.sub.2CH.sub.2OMe).sub.2Ln(BH.sub.4).sup.27,28--none
has been described as volatile. Volatile lanthanum-containing
molecules that do not contain boron atoms have been extensively
studied for the deposition of thin films of lanthanum oxides
(Ln.sub.2O.sub.3) that are high-k dielectric materials and
high-temperature superconductors
(LnBa.sub.2Cu.sub.3O.sub.7-.delta.). None of these precursors, such
as lanthanum .beta.-diketonates,.sup.29,30
cyclopentadienyls,.sup.31-33 and amides.sup.34-36 have been used
for the CVD of LnB.sub.6 phases.
[0324] Here we report the synthesis and characterization of
lanthanide complexes of the N,N-dimethyldiboranamide ligand
[H.sub.3BNMe.sub.2BH.sub.3].sup.-. Among the compounds prepared are
the homoleptic compounds M.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6,
where M=Y and Dy, and their mononuclear adducts with
tetrahydrofuran. These molecules, which possess a boron-to-metal
ratio of 6 and are readily volatile below 100.degree. C., are
potential CVD precursors for the low-temperature growth of
LnB.sub.6.
Results and Discussion
[0325] Synthesis and Characterization of
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 and
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0326] The solid state reaction of YCl.sub.3 and sodium
N,N-dimethyldiboranamide, Na(H.sub.3BNMe.sub.2BH.sub.3), at room
temperature, followed by sublimation at 100.degree. C. in vacuum,
affords the dinuclear yttrium complex,
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 1. A similar reaction
with DyCl.sub.3 yields the dysprosium analogue
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 2. This synthetic
method, which involves a solid state reaction of the starting
materials at room temperature, perforce avoids the formation of
solvated complexes.
2MCl.sub.3+6Na(H.sub.3BNMe.sub.2BH.sub.3).sub.2-.fwdarw.M.sub.2(H.sub.3B-
NMe.sub.2BH.sub.3).sub.6+6NaCl [0327] M=Y (1) [0328] M=Dy (2)
[0329] The infrared spectrum of 1 features a strong band at 2424
cm.sup.-1 due to terminal B-H stretches, and two strong bands at
2220 and 2166 cm.sup.-1 due to the bridging B-H stretches. Very
similar B-H stretches at 2416, 2216, and 2170 cm.sup.-1 are
observed for the dysprosium analogue 2. These B-H stretching bands
closely resemble those seen in homoleptic magnesium and transition
metal complexes of the diboranamide ligand..sup.37
[0330] The .sup.1H NMR spectrum of the yttrium complex 1 in
CD.sub.2Cl.sub.2 at 20.degree. C. shows two signals, a singlet at
.delta. 2.42 for the NMe.sub.2 group and a broad 1:1:1:1 quartet
(J.sub.BH=84 Hz) at .delta. 2.06 for the BH.sub.3 groups (FIG. 12).
The complex exhibits one signal for the NMe.sub.2 groups in its
.sup.13C NMR spectrum, and one signal at .delta. 50.8 in its
.sup.11B NMR spectrum. At -80.degree. C., the .sup.1H NMR spectrum
exhibits a singlet for the NMe.sub.2 groups and a broad unresolved
signal for the BH.sub.3 groups; the latter are broadened by rapid
spin-lattice relaxation caused by the quadrupolar .sup.11B and
.sup.10B nuclei. The presence of only one environment for the
diboranamide ligands contrasts with the presence of two different
environments in the solid state (see below). Evidently, the complex
either dissociates to monomers in solution, or the terminal and
bridging diboranamide groups are rapidly exchanging with one
another even at -80.degree. C. For the paramagnetic dysprosium
complex 2, the room-temperature .sup.1H NMR spectrum exhibits a
paramagnetically shifted and broadened resonance for the NMe.sub.2
group at .delta. 97.5 (fwhm=250 Hz) but no signals for the BH.sub.3
groups; the resonances for the latter must be very broad and
shifted by their proximity to the paramagnetic center.
[0331] Crystal Structures of
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6 and
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0332] The molecular structures of 1 and 2 are presented in FIGS.
13 and 14; crystallographic data and selected bond distances and
angles are listed in Tables 1-3. The yttrium complex 1 adopts a
dimeric structure in which two yttrium centers are connected by two
bridging H.sub.3BNMe.sub.2BH.sub.3 ligands; each yttrium center
also bears two terminal diboranamide groups, which are chelating.
The only other complex in which diboranamide ligands can be said to
bridge between two metal centers is
[Na(H.sub.3BNMe.sub.2BH.sub.3)].sub.5.thf, but in this salt the
diboranamide ligands actually interact in a complex way with two or
three sodium cations..sup.38 The Y . . . Y separation in 1 is 6.03
.ANG.. If each BH.sub.3 group is considered as occupying one
coordination site, each yttrium center is six-coordinate and adopts
a distorted octahedral geometry. Two hydrogen atoms from each boron
atom are bonded to the yttrium center, so that there are a total of
12 Y-H interactions.
[0333] The Y . . . B distances to the terminal diboranamide groups
lie in the range 2.701(7)-2.763(7) .ANG. and average 2.731(20)
.ANG.. For each of these ligands, the four-membered Y-B-N-B rings
are essentially planar, as seen in other diboranamide complexes in
which the BH.sub.3 groups bind to the metal centers by means of two
hydrogen bridges..sup.37 Interestingly, the bridging diboranamide
ligands are not bound symmetrically to two yttrium centers: there
are two short Y . . . B distances of 2.672(7) and 2.734(7) .ANG.
(Y2 . . . B12 and Y1 . . . B21) and two longer Y . . . B distances
of 2.837(7) and 2.853(7) .ANG. (Y1 . . . B11 and Y2 . . . B22). The
B-N-B planes of the bridging diboranamide groups are not parallel
to Y-Y axis and instead pass more closely to one yttrium center
than the other: Y1 and Y2 are displaced 0.49 and 1.32 .ANG.,
respectively from the B11-N11-B12 plane, whereas they 1.44 and 0.43
.ANG., respectively, from the B22-N21-B22 plane. The Y-B-N angles
of 145.12 and 147.56.degree. for the longer Y . . . B distances are
more obtuse by about 10.degree. than those of 134.39 and
134.82.degree. for the shorter Y . . . B distances.
[0334] The average B-Y-B angle of 55.6(4).degree. within each of
the two terminal diboranamide ligands is significantly smaller than
all the other B-Y-B angles, as expected for a chelating ligand with
a small bite. In particular, the B-Y-B angle between the two
bridging diboranamide ligands are 90.7(2) and 91.192).degree.,
which suggest that the BH.sub.3 "ends" of the two bridging
diboranamide ligands jointly occupy more steric volume than would a
chelating ligand. This stereochemical effect probably is related to
the reasons 1 does not adopt a monomeric structure with three
chelating diboranamide ligands: such a structure would not
sufficiently saturate the coordination sphere of the large yttrium
center. All of the B-N-B, B-N-C, and C-N-C angles within the
diboranamide groups are close to ideal tetrahedral value of
109.5.degree., except for the B-N-B angles within the bridging
ligands, 113.7(5) and 112.1(5).degree., which are somewhat more
obtuse.
[0335] The structure of the dysprosium analogue 2 is identical to
that of 1: each dysprosium center is coordinated to two terminal
and two bridging diboranamide ligands. The Dy . . . Dy separation
is 6.01 .ANG.. The bridging ligands are again bound
unsymmetrically: the shorter Dy . . . B distances are 2.68 and 2.73
.ANG. and longer Dy . . . B distances are identical at 2.84 .ANG..
The Dy . . . B distances for the terminal diboranamide groups lie
in a range 2.70-2.76 .ANG. and average 2.73 .ANG.. The B-Dy-B
angles for the terminal ligands average 55.6.degree., which is
smaller than the average B-Dy-B angle of 91.0.degree. for the
bridging diboranamide ligands, as seen in 1.
[0336] Synthesis and Characterization of
M(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) Complexes.
[0337] Treatment of YCl.sub.3 with Na(H.sub.3BNMe.sub.2BH.sub.3) in
tetrahydrofuran affords the monomeric thf adduct
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 3, which can be isolated
as white crystals by sublimation at 90.degree. C. and 0.05 Torr.
Carrying out a similar reaction with DyCl.sub.3 in thf yields the
dysprosium analogue Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).sub.4.
Both complexes are air- and water-sensitive.
MCl.sub.3+3Na(H.sub.3BNMe.sub.2BH.sub.3).sub.2+thf-.fwdarw.M(H.sub.3BNMe-
.sub.2BH.sub.3).sub.3(thf)+3NaCl [0338] M=Y (3) [0339] M=Dy (4)
[0340] The infrared spectrum of 3 shows two strong bands in the B-H
stretch region: a strong terminal B-H stretch at 2399 cm.sup.-1 and
three strong bridging B-H stretches at 2294, 2227, and 2177
cm.sup.-1. Similar strong bands are observed in the IR spectrum of
4 at 2410, 2280, 2223 and 2176 cm.sup.-1. The .sup.1H NMR spectrum
of 3 at 20.degree. C. shows a singlet at .delta. 2.37 for the
NMe.sub.2 group, a 1:1:1:1 quartet at .delta. 2.00 for the BH.sub.3
group, and characteristic resonances for the .alpha. and .beta.
protons of the thf ligand at .delta. 3.98 and 1.90. The variable
temperature .sup.1H{.sup.11B} NMR spectrum between -80 and
20.degree. C. shows no evidence of dynamic behavior. The
paramagnetic dysprosium(III) complex 4 shows shifted and broadened
signals for the NMe.sub.2 groups at .delta. -19.50 (fwhm=250 Hz)
and for the .beta.-CH.sub.2 protons of the thf molecule at .delta.
-29.07 (fwhm=150 Hz). No resonances for the BH.sub.3 groups or the
.alpha.-CH.sub.2 protons of thf could be located.
[0341] Crystal Structures of
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) and
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0342] The molecular structure of 3 and 4 are illustrated in FIGS.
15 and 16; crystallographic data and selected bond distances and
angles are listed in Tables 1, 4, and 5. For the yttrium complex 3,
there are two crystallographically independent molecules in the
unit cell and they have very similar bond lengths and angles. The
yttrium center is coordinated to three chelating
H.sub.3BNMe.sub.2BH.sub.3 ligands and one thf molecule; if we
consider each BH.sub.3 group to occupy one coordination site, the
metal center is 7-coordinate. Each BH.sub.3 group is bound to the
yttrium center by means of two hydrogen bridges, thus forming a
total of twelve Y-H contracts. The Y-H distances fall in the range
2.23(4)-2.58(6) .ANG. and average 2.39(16) .ANG.. The Y . . . B
distances average 2.82(2) .ANG., which is about 0.1 .ANG. longer
than the corresponding distances to the chelating diboranamide
ligands in unsolvated 1. The average B-Y-B angle of 53.4(3).degree.
within each diboranamide ligand is 3.degree. smaller than that of
56.5.degree. in 1. The longer Y . . . B distances and smaller B-Y-B
angles in 3 vs. 1 probably reflect the steric crowding caused by
the additional thf ligand.
[0343] The Y-H and Y . . . B distances in 1 and 3 can be compared
with those in yttrium tetrahydroborate (BH.sub.4) complexes; among
these are Y(BH.sub.4).sub.3(thf).sub.3,.sup.39
(C.sub.5H.sub.4CH.sub.2CH.sub.2OMe).sub.2Y(BH.sub.4),.sup.40
(C.sub.5Me.sub.4Et).sub.2Y(BH.sub.4)(thf),.sup.41 and
(MeOCH.sub.2CH.sub.2C.sub.9H.sub.6).sub.2Y(BH.sub.4)..sup.42 The
average Y-H distance of 2.39(16) .ANG. in 3 is somewhat longer than
that of 2.31(19) .ANG. for these yttrium tetrahydroborates.
Moreover, the Y . . . B distances of 2.672(7)-2.853(7) .ANG. in 1
and 2.82(2) .ANG. in 3 are longer than those of 2.669(4)-2.693(8)
.ANG. observed for yttrium complexes containing bidentate BH.sub.4
groups. Presumably, steric crowding cause by the high coordination
numbers are responsible for the longer distances seen in 1 and 3,
whose metal centers are bound to twelve and thirteen atoms,
respectively, vs. 8 to 10 for the reference compounds above.
[0344] The structure of the dysprosium complex 4 is identical to
that of yttrium complex 3: the dysprosium center is ligated by
three chelating diboranamide ligands and one thf molecule. The Dy .
. . B distances in 4, which average 2.821(16) .ANG., are longer
than the same distances in 2 by nearly 0.09 .ANG.. The three B-Dy-B
angles are nearly identical and average 53.4(3).degree., which is
smaller than that of 55.6.degree. in 2. The bond length and angle
differences seen for 4 vs 2 again reflect the higher degree of
steric congestion caused by the presence of the additional thf
ligand and higher effective coordination number in 4.
Experimental Section
[0345] All experiments were carried out under vacuum or under argon
by using standard Schlenk techniques. Solvents were distilled under
nitrogen from sodium/benzophenone immediately before use. The
starting material Na(H.sub.3BNMe.sub.2BH.sub.3) was prepared by a
literature procedure..sup.38 YCl.sub.3 and DyCl.sub.3 were used as
received from Aldrich. Microanalyses were performed by the
University of Illinois Microanalytical Laboratory. The IR spectra
were recorded on a Nicolet Impact 410 instrument as Nujol mulls
between KBr plates. The .sup.1H and .sup.13C NMR data were
collected on Varian Gemini 500 instrument at 499.699 MHz and
125.663 MHz, respectively. The .sup.11B NMR data were collected on
General Electric GN300WB instrument at 300 MHz. Chemical shifts are
reported in 6 units (positive shifts to high frequency) relative to
tetramethylsilane (.sup.1H, .sup.13C) or BF.sub.3.Et.sub.2O
(.sup.11B). Field ionization (FI) mass spectra were recorded on a
Micromass 70-VSE mass spectrometer. The shapes of all peak envelops
correspond with those calculated from the natural abundance
isotopic distributions.
[0346] Hexakis(N,N-dimethyldiboranamido)diyttrium(III),
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 1.
[0347] Solid YCl.sub.3 (0.73 g, 3.8 mmol) and
Na(H.sub.3BNMe.sub.2BH.sub.3) (1.26 g, 13.3 mmol) were ground
together briefly in a mortar and pestle. The dry solid mixture was
transferred to a 100 mL round-bottom Schlenk flask, and 30-40 steel
balls (4.5-mm diameter) were added. The flask was gently agitated
for 30 min. Sublimation at 100.degree. C. in vacuum afforded white
crystals. Yield: 0.22 g (19%). .sup.1H NMR (CD.sub.2Cl.sub.2,
20.degree. C.): .delta. 2.42 (s, 36H, NMe.sub.2), 2.06 (q,
J.sub.BH=84 Hz, 36H, BH.sub.3). .sup.13C{.sup.1H} NMR
(CD.sub.2Cl.sub.2, 20.degree. C.): .delta. 51.1 (s).
.sup.11B{.sup.1H} NMR (CD.sub.2Cl.sub.2, 20.degree. C.): .delta.
50.8 (s). Anal. Calcd for C.sub.6H.sub.36N.sub.3B.sub.6Y: C, 23.7;
H, 11.9; N, 12.8; B, 21.3; Y, 29.2. Found: C, 22.9; H, 11.1; N,
12.8; B, 19.5; Y, 28.0. IR (cm.sup.-1): 2424 vs, 2336 m, 2273 m,
2220 s, 2166 s, 2058 sh, 1399 w, 1335 s, 1286 s, 1237 w, 1212 w,
1170s, 1015 s, 969 m, 927 m, 902 m, 841 m, 814 s, 464 s.
[0348] Hexakis(N,N-dimethyldiboranamido)didysprosium(III),
Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 2.
[0349] Solid DyCl.sub.3 (0.56 g, 2.1 mmol) and solid
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.65 g, 6.7 mmol) and were ground
together briefly in a mortar and pestle. The dry solid mixture was
transferred to a 100 mL round-bottom Schlenk flask, and 30-40 steel
balls (4.5-mm diameter) were added. The flask was gently agitated
by hand for 30 min. Sublimation at 95.degree. C. in vacuum afforded
white crystals. Yield: 0.19 g (24%). Anal. Calcd for
C.sub.6H.sub.36N.sub.3B.sub.6Dy: C, 19.1; H, 9.61; N, 11.1. Found:
C, 19.0; H, 9.62; N, 10.8. MS (FI): m/z 377.3 (M/2-1).sup.+.
.sup.1H NMR (C.sub.6D.sub.6, 20 (C): .delta. 97.5 (s, fwhm=250 Hz,
NMe.sub.2). IR (cm.sup.-1): 2416 vs, 2334 m, 2272 m, 2216 s, 2170
s, 2061 w, 1282 vs, 1237 s, 1218 m, 1183 m, 1162 vs, 1130 m, 1031
w, 1020 s, 973 w, 925 m, 904 m, 844 w, 814 w, 463 s.
[0350] Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)yttrium(III),
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3 thf), 3.
[0351] To a solution of YCl.sub.3 (1.07 g, 5.5 mmol) in
tetrahydrofuran (30 mL) at room temperature was added a solution of
Na(H.sub.3BNMe.sub.2BH.sub.3) (1.56 g, 16.5 mmol) in
tetrahydrofuran (30 mL). After the reaction mixture had been
stirred for 10 h at room temperature, the solvent was removed in
vacuum. Sublimation at 90.degree. C. and at 0.05 Torr afforded
white crystals. Yield: 0.76 g (37%). .sup.1H NMR (CD.sub.2Cl.sub.2,
20.degree. C.): .delta. 3.98 (m, 4H, OCH.sub.2), 2.37 (s, 18H,
NMe.sub.2), 2.00 (q, J.sub.BH=84 Hz, 18H, 8H.sub.3), 1.90 (m, 4H,
CH.sub.2). Anal. Calcd for C.sub.10H.sub.44N.sub.3B.sub.6OY: C,
31.9; H, 11.8; N, 11.2. Found: C, 30.1; H, 11.8; N, 11.5. IR
(cm.sup.-1): 2399 vs, 2294 m, 2227 s, 2177 w, 2060 sh, 1283 s, 1241
s, 1217 s, 1189 w, 1171 s, 1137 s, 1020 s, 924 m, 904 w, 856 m, 837
w, 819 w, 666 w.
[0352]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)dysprosium(III),
Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 4.
[0353] To a solution of DyCl.sub.3 (0.50 g, 1.9 mmol) in
tetrahydrofuran (30 mL) at -78.degree. C. was added a solution of
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.60 g, 6.3 mmol) in tetrahydrofuran
(30 mL). The reaction mixture was stirred at -78.degree. C. for 30
min and then was allowed to warm slowly to room temperature. After
the reaction mixture had been refluxed at 75.degree. C. for 24 h,
the solvent was removed in vacuum. The white residue was extracted
with pentane (2.times.50 mL), and the extract was filtered and
concentrated to ca. 10 mL. Crystallization at -20.degree. C.
afforded white crystals. Yield: 0.47 g (63%). .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. -19.50 (s, fwhm=250 Hz,
18H, NMe.sub.2); -29.07 (s, fwhm=150 Hz, 4H, .beta.-CH.sub.2).
Anal. Calcd for C.sub.10H.sub.44N.sub.3B.sub.6ODy: C, 26.7; H,
9.86; N, 9.34; B, 14.4; Dy, 36.1. Found: C, 26.1; H, 10.1; N, 8.73;
B, 15.0; Dy, 33.8. IR (cm.sup.-1): 2410 vs, 2280 m, 2223 s, 2178 w,
2064 w, 1279 vs, 1238 m, 1217 w, 1168 s, 1139 s, 1017 vs, 927 s 902
w, 836 s, 817 w, 666 w. Single crystals for the X-ray diffraction
study were grown by sublimation at 90.degree. C. and at 0.05
Torr.
[0354] X-ray Structure Determinations..sup.43
[0355] Single crystals of all four compounds, grown by sublimation,
were mounted on glass fibers with Krytox oil (DuPont), and
immediately cooled to -80.degree. C. in a cold nitrogen gas stream
on the diffractometer. Data for 1-4 were collected with an area
detector by using the measurement parameters listed in Table 1. The
measured intensities were reduced to structure factor amplitudes
and their esd's by correction for background, and Lorentz and
polarization effects. Systematically absent reflections were
deleted and symmetry-equivalent reflections were averaged to yield
the sets of unique data. The analytical approximations to the
scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. All structures were solved using direct methods
(SHELXTL). The correct positions for all non-hydrogen atoms of 1-4
were deduced from E-maps. The analytical approximations to the
scattering factors were used, and all structure factors were
corrected for both the real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. Final refinement parameters for 1-4 are given in Table 1. A
final analysis of variance between observed and calculated
structure factors showed no apparent errors. Subsequent discussions
for 1-4 will be divided into individual paragraphs.
[0356] Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 1.
[0357] Systematic absences for 0kl (k+l.noteq.2n) and h0l
(h.noteq.2n) were consistent with space groups Pna2.sub.1 and Pnma;
the non-centrosymmetric Pna2.sub.1 was shown to be the correct
choice by successful refinement of the proposed model. All 9025
unique reflections were used in the least squares refinement.
Although corrections for crystal decay were unnecessary, a
face-indexed absorption correction was applied. The quantity
minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.o.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0168P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. Hydrogen atoms were placed in
idealized positions; hydrogen atoms attached to boron and methyl
hydrogen atoms were placed in idealized tetrahedral locations with
B-H=1.15 .ANG. and C-H=0.98 .ANG., respectively; the BH.sub.3 and
CH.sub.3 groups were allowed to rotate about the B-N and the C-N
bonds, respectively, to find the best least-squares positions.
Displacement parameters for the hydrogen atoms were set equal to
1.5 times U.sub.eq for the attached carbon or boron atom. No
correction for isotropic extinction was necessary. Analysis of the
diffraction intensities suggested that the crystal was twinned by
inversion; therefore, the intensities were calculated from the
equation l.sub.calc=xl.sub.hkl+(1-x)/.sub.h'k'l', where x is a
scale factor that relates the volumes of the inversion-related twin
components. The scale factor refined to a value of 0.83(1).
Successful convergence was indicated by the maximum shift/error of
0.001 for the last cycle. Final refinement parameters are given in
Table 1. The largest peak in the final Fourier difference map (1.40
e.ANG..sup.-3) was located 1.80 .ANG. from H(2A). A final analysis
of variance between observed and calculated structure factors
showed no apparent errors.
[0358] Dy.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6, 2.
[0359] Systematic absences for 0kl (k+l.noteq.2n) and h0l
(h.noteq.2n) were consistent with space groups Pna2.sub.1 and Pnma;
the non-centrosymmetric Pna2.sub.1 was shown to be the correct
choice by successful refinement of the proposed model.
Systematically absent reflections were deleted and symmetry
equivalent reflections were averaged; the 2 0 0 reflection was
obscured by the beamstop and was deleted to yield the set of 9596
unique data. No corrections for absorption or crystal decay were
applied.
[0360] Hydrogen atoms were placed in idealized positions; hydrogen
atoms attached to boron and methyl hydrogen atoms were placed in
idealized tetrahedral locations with B-H=1.15 .ANG. and C-H=0.98
.ANG., respectively; the BH.sub.3 and CH.sub.3 groups were allowed
to rotate about the B-N and the C-N bonds, respectively, to find
the best least-squares positions. Displacement parameters for the
hydrogen atoms were set equal to 1.5 times U.sub.eq for the
attached boron or carbon atom. Despite these efforts, however, the
weighted R-factor remained unacceptably high (>0.2), two
unusually large peaks (.+-.17 e/.ANG..sup.3) remained in the
difference map that appeared to be "ghosts" related to the two
dysprosium atoms by the transformation (x+0.33333, 0.5-y, z), and
reflections of the form hkl (h=3n) were systematically far more
intense than calculated, especially but not exclusively when l=2n
and h+k=2n. A reinspection of the original data frames ruled out
the possibility that the crystal was a pseudo-merohedral twin in
which only the h=3n reflections were affected by overlap. We
concluded that the crystal was probably affected by a kind of
stacking fault; the molecules are lined up in columns along the
x-axis, with their Dy-Dy vectors aligned along this direction also.
It seemed possible that, part of the time, the molecules in one
column could be displaced by a fractional cell distance along the
x-axis and still pack well. As a last measure, we deleted all
reflections with h=3n, leaving 6464 unique data. Immediately,
wR.sup.2 decreased to -0.15 and the sizes of the ghost peaks
decreased to .+-.7 e/.ANG..sup.3. A stacking fault model was
constructed in which a second molecule was added that was related
to the first by the transformation (x+0.33333, 0.5-y, z). This
second molecule was treated as a rigid group in which all the
non-hydrogen atoms were assigned a common isotropic displacement
parameter and a common partial site occupancy factor. The site
occupancy factors for the major and minor locations were
constrained to sum to 1; the SOF for the major site refined to
0.927(1). Note that this model did not afford intensities for the
h=3n reflections that agreed with the observed values.
[0361] The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.043P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F.sub.c.sup.2)/3. No correction for isotropic
extinction was necessary. The analytical approximations to the
scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. Analysis of the diffraction intensities suggested that
the crystal was twinned by inversion; therefore, the intensities
were calculated from the equation
l.sub.calc=xl.sub.hki+(1-x)l.sub.h'k'l', where x is a scale factor
that relates the volumes of the inversion-related twin components.
The scale factor refined to a value of 0.62(3). Successful
convergence was indicated by the maximum shift/error of 0.002 for
the last cycle. Final refinement parameters are given in Table 1.
The largest peak in the final Fourier difference map (1.12
e.ANG..sup.-3) was located 0.60 from Dy(2). A final analysis of
variance between observed and calculated structure factors showed
no apparent errors.
[0362] Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 3.
[0363] Systematic absences for 0kl (k+l.noteq.2n) and h0l
(l.noteq.2n) were consistent with space groups Pca2.sub.1 and Pbcm;
the non-centrosymmetric Pca2.sub.1 was shown to be the correct
choice by successful refinement of the proposed model. All 8605
unique reflections were used in the least squares refinement.
Although corrections for crystal decay were unnecessary, a
face-indexed absorption correction was applied. The quantity
minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.o.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0191P).sup.2+2.000P}.sup.-1
and P=(F.sub.o.sup.2+2F.sub.o.sup.2)/3. Hydrogen atoms attached to
boron were located in the difference maps, and their positions were
refined with independent isotropic displacement parameters. The B-H
distances to bridging hydrogen were constrained to equal within
0.05 .ANG.; similar constraints were applied for chemically related
B-H distances to the terminal hydrogen atoms. The methyl hydrogen
atoms were placed in idealized locations with C-H=0.98 .ANG. and
their displacement parameters were set equal to 1.5 times U.sub.eq
for the attached carbon atom; the CH.sub.3 groups were allowed to
rotate about the C-N axis to find the best least-squares positions.
Methylene hydrogen atoms were also placed in idealized locations
with C-H=0.99 .ANG. and displacement parameters set equal to 1.2
times U.sub.eq for the attached carbon atom. No correction for
isotropic extinction was necessary. Analysis of the diffraction
intensities suggested that the crystal was twinned by inversion;
therefore, the intensities were calculated from the equation
l.sub.calc=xl.sub.hkl+(1-x)l.sub.h'k'l', where x is a scale factor
that relates the volumes of the inversion-related twin components.
The scale factor refined to a value of 0.879(6). Successful
convergence was indicated by the maximum shift/error of 0.002 for
the last cycle. Final refinement parameters are given in Table 1.
The largest peak in the final Fourier difference map (0.42
e.ANG..sup.-3) was located 1.18 .ANG. from C(22). A final analysis
of variance between observed and calculated structure factors
showed no apparent errors.
[0364] Dy(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf), 4.
[0365] Systematic absences for 0kl (k+l.noteq.2n) and h0l
(l.noteq.2n) were consistent with space groups Pca2.sub.1 and Pbcm;
the non-centrosymmetric Pca2.sub.1 was shown to be the correct
choice by successful refinement of the proposed model. All 10934
unique reflections were used in the least squares refinement.
Although corrections for crystal decay were unnecessary, a
face-indexed absorption correction was applied. The quantity
minimized by the least-squares program was
.SIGMA.w(F.sub.o.sup.2-F.sub.c.sup.2).sup.2, where
w={[.sigma.(F.sub.o.sup.2)].sup.2+(0.0316P).sup.2}.sup.-1 and
P=(F.sub.o.sup.2+2F2)/3. Hydrogen atoms attached to boron were
placed in idealized tetrahedral locations, constraining the B-H
distances to the bridging hydrogen to be equal within 0.005 .ANG.;
similar constraints were applied for chemically related B-H
distances to the terminal hydrogen atoms. The BH.sub.3 groups were
allowed to rotate about the B-N bonds to find the best
least-squares positions. The methyl hydrogen atoms were placed in
idealized tetrahedral locations with C-H=0.98 .ANG.; the CH.sub.3
groups were allowed to rotate about the C-N bonds to find the best
least-squares positions. Displacement parameters for the methyl and
borane hydrogen atoms were set equal to 1.5 times U.sub.eq for the
attached carbon or boron atom. Methylene hydrogen atoms were placed
in idealized locations with C-H=0.99 .ANG. and their displacement
parameters set equal to 1.2 times U.sub.eq for the attached carbon
atom. No correction for isotropic extinction was necessary.
Analysis of the diffraction intensities suggested that the crystal
was twinned by inversion; therefore, the intensities were
calculated from the equation
l.sub.calc=xl.sub.hkl+(1-x)l.sub.h'k'l', where x is a scale factor
that relates the volumes of the inversion-related twin components.
The scale factor refined to a value of 0.63(1). Successful
convergence was indicated by the maximum shift/error of 0.002 for
the last cycle. Final refinement parameters are given in Table 1.
The largest peak in the final Fourier difference map (1.02
e.ANG..sup.-3) was located 1.21 .ANG. from Dy(1). A final analysis
of variance between observed and calculated structure factors
showed no apparent errors.
REFERENCES
[0366] 1. Roy, P. K.; Moon, A.; Mima, K.; Nakai, S.; Fujita, M.;
Imasaki, K.; Yamanaka, C.; Yasuda, E.; Watanabe, T.; Ohigashi, N.;
Okuda, Y.; Tsunawaki, Y. Rev. Sci. Instrum. 1996, 67, 4098-4102.
[0367] 2. Tennant, D. M.; Swanson, L. W. J. Vac. Sci. Technol., B
1989, 7, 93-97. [0368] 3. Yamabe, M.; Furukawa, Y.; Inagaki, T. J.
Vac. Sci. Technol., A 1984, 2, 1361-1364. [0369] 4. Doy, T. K.;
Kasai, T.; Ohmori, H. J. Ceram. Soc. Jpn. 1999, 107, 502. [0370] 5.
Schmidt, P. H.; Longinotti, L. D.; Joy, D. C.; Ferris, S. D.;
Leamy, H. J.; Fisk, Z. J. Vac. Sci. Technol. 1978, 15, 1554-1560.
[0371] 6. Verhoeven, J. D.; Gibson, E. D.; Noack, M. A. J. Appl.
Phys. 1976, 47, 5105-5106. [0372] 7. Gesley, M.; Swanson, L. W.
Surf. Sci. 1984, 146, 583-599. [0373] 8. Lafferty, J. M. J. Appl.
Phys. 1951, 22, 299-309. [0374] 9. Samsonov, G. V. Plenum Press
Handbooks of High Temperature Materials, No. 2. Properties Index,
1964. [0375] 10. Schelm, S.; Smith, G. B.; Garrett, P. D.; Fisher,
W. K. J. Appl. Phys. 2005, 97, 124314-8. [0376] 11. Rinzler, A. G.;
Hafner, J. H.; Nikolaev, P.; Lou, L.; Kim, S. G.; Tomanek, D.;
Nordlander, P.; Colbert, D. T.; Smalley, R. E. Science 1995, 269,
1550-1553. [0377] 12. Wong, K. W.; Zhou, X. T.; Au, F. C. K.; Lai,
H. L.; Lee, C. S.; Lee, S. T. Appl. Phys. Lett. 1999, 75,
2918-2920. [0378] 13. Lee, Y. H.; Choi, C. H.; Jang, Y. T.; Kim, E.
K.; Ju, B. K.; Min, N. K.; Ahn, J. H. Appl. Phys. Lett. 2002, 81,
745-747. [0379] 14. Li, Y. B.; Bando, Y.; Golberg, D.; Kurashima,
K. Appl. Phys. Lett. 2002, 81, 5048-5050. [0380] 15. Late, D. J.;
More, M. A.; Joag, D. S.; Misra, P.; Singh, B. N.; Kukreja, L. M.
Appl. Phys. Lett. 2006, 89. [0381] 16. Nakamoto, M.; Fukuda, K.
Appl. Surf. Sci. 2002, 202, 289-294. [0382] 17. Waldhauser, W.;
Mitterer, C.; Laimer, J.; Stori, H. Surf. Coat. Technol. 1998, 98,
1315-1323. [0383] 18. Mroczkowski, S. J. J. Vac. Sci. Technol. A
1991, 9, 586-590. [0384] 19. Yutani, A.; Kobayashi, A.; Kinbara, A.
Appl. Surf. Sci. 1993, 70-1, 737-741. [0385] 20. Okamoto, Y.; Aida,
T.; Shinada, S. Jpn. J. Appl. Phys. 1 1987, 26, 1722-1726. [0386]
21. Zhang, H.; Zhang, Q.; Tang, J.; Qin, L. C. J. Am. Chem. Soc.
2005, 127, 8002-8003. [0387] 22. Zhang, H.; Zhang, Q.; Zhao, G.;
Tang, J.; Zhou, O.; Qin, L. C. J. Am. Chem. Soc. 2005, 127,
13120-13121. [0388] 23. Zhang, H.; Tang, J.; Zhang, Q.; Zhao, G.;
Yang, G.; Zhang, J.; Zhou, O.; Qin, L. C. Adv. Mater. 2006, 18,
87-91. [0389] 24. Zhang, H.; Zhang, Q.; Tang, J.; Qin, L. C. J. Am.
Chem. Soc. 2005, 127, 2862-2863. [0390] 25. Kher, S. S.; Spencer,
J. T. J. Phys. Chem. Solids 1998, 59, 1343-1351. [0391] 26.
Hagimura, A.; Kato, A. Nippon Kagaku Kaishi 1980, 1108-1113. [0392]
27. Ephritikhine, M. Chem. Rev. 1997, 97, 2193-2242. [0393] 28.
Tiitta, M.; Niinisto, L. Chem. Vap. Deposition 1997, 3, 167-182.
[0394] 29. Edleman, N. L.; Wang, A.; Belot, J. A.; Metz, A. W.;
Babcock, J. R.; Kawaoka, A. M.; Ni, J.; Metz, M. V.; Flaschenriem,
C. J.; Stern, C. L.; Liable-Sands, L. M.; Rheingold, A. L.;
Markworth, P. R.; Chang, R. P. H.; Chudzik, M. P.; Kannewurf, C.
R.; Marks, T. J. Inorg. Chem. 2002, 41, 5005-5023. [0395] 30. Lo
Nigro, R.; Malandrino, G.; Toro, R. G.; Fragala, I. L. Chem. Vap.
Deposition 2006, 12, 109-124. [0396] 31. Weber, A.; Suhr, H.;
Schumann, H.; Kohn, R. D. Appl. Phys. A: Mater. Sci. Process. 1990,
51, 520-525. [0397] 32. Paivasaari, J.; Niinisto, J.; Arstila, K.;
Kukli, K.; Putkonen, M.; Niinisto, L. Chem. Vap. Deposition 2005,
11, 415-419. [0398] 33. Niinisto, J.; Putkonen, M.; Niinisto, L.
Chem. Mater. 2004, 16, 2953-2958. [0399] 34. Gordon, R. G.; Becker,
J.; Hausmann, D.; Suh, S. Chem. Mater. 2001, 13, 2463-2464. [0400]
35. Just, O.; Rees, W. S. Adv. Mater. Opt. Electr. 2000, 10,
213-221. [0401] 36. Rees, W. S.; Just, O.; Van Derveer, D. S. J.
Mater. Chem. 1999, 9, 249-252. [0402] 37. See Example 13. [0403]
38. Noth, H.; Thomas, S. Eur. J. Inorg. Chem. 1999, 1373-1379.
[0404] 39. Segal, B. G.; Lippard, S. J. Inorg. Chem. 1978, 17,
844-850. [0405] 40. Laske, D. A.; Duchateau, R.; Teuben, J. H.;
Spek, A. L. J. Organomet. Chem. 1993, 462, 149-153. [0406] 41.
Herbert Schumann, M. R. K. J. D. S. M. Z. Anorg. Allg. Chem. 1998,
624, 1811-1818. [0407] 42. Qian, C.-T.; Zou, G.; Nie, W.-L.; Sun,
J.; Lemenovskii, D. A.; Borzov, M. V. Polyhedron 2000, 19,
1955-1959. [0408] 43. For details of the crystallographic methods
used see: Brumaghim, J. L.; Priepot, J. G.; Girolami, G. S.
Organometallics 1999, 18, 2139-2144.
Example 15
Catalyzed Chemical Vapor Deposition of Titanium-Doped Magnesium
Diboride Thin Films from Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
Introduction
[0409] The incorporation of superconductors into integrated
circuits is the subject of considerable interest due to the promise
of creating ultrafast digital logic devices:.sup.1,2 rapid
single-flux quantum logic circuits made of niobium have shown that
the clock speeds of the superconducting devices can reach up to 770
GHz..sup.3,4 Josephson junctions, which are the core elements of
these superconducting circuits, are typically constructed from thin
films of niobium-based materials owing to their reliable properties
at 4.2 K. Cuprate superconductors, whose higher critical
temperatures would enable cooling with liquid nitrogen rather than
liquid helium, have proven difficult to incorporate into integrated
circuits owing to their short coherence lengths, their electrical
anisotropy, and the complexities associated with depositing
stoichiometric thin films containing four or more different
chemical elements..sup.5-7
[0410] Cuprate materials aside, the superconductor with the highest
known critical temperature is magnesium diboride (MgB.sub.2), which
has a superconducting transition temperature of 39 K,.sup.8 a long
coherence length of .about.5 nm,.sup.9 and a large energy
gap..sup.10 In combination with the simple stoichiometry, these
properties strongly suggest that superconducting integrated
circuits made of MgB.sub.2 should operate faster at higher
temperatures than current devices based on niobium.
[0411] The deposition of MgB.sub.2 thin films is complicated by one
major challenge: loss of Mg from the MgB.sub.2 phase at growth
temperatures above ca. 400.degree. C..sup.11 If enough Mg is lost,
the MgB.sub.2 films become non-superconducting. Several strategies
to overcome this problem have been reported. Kang and co-workers
have produced MgB.sub.2 films by depositing amorphous boron
followed by reaction with Mg vapor at 900.degree. C..sup.12
Although this method has produced high-quality MgB.sub.2 films with
a critical temperature T.sub.c of 39 K, the ex-situ high
temperature annealing process must be conducted in a sealed
tantalum tube, which makes this method less attractive for
producing multilayer thin films on a large scale. Ueda et al. have
produced MgB.sub.2 thin films with a T.sub.c of ca. 38 K by
co-evaporation of Mg and B at 240 to 270.degree. C..sup.13 Zeng et
al. have grown MgB.sub.2 thin films by an in situ hybrid
physical-chemical vapor deposition (HP-CVD) method in which
B.sub.2H.sub.6 reacts with Mg vapor generated from Mg chips placed
near the substrate..sup.14 The main drawback to employing this
latter approach in the fabrication of multilayer devices is the
high deposition temperature of ca. 750.degree. C., which will
promote undesirable interfacial reactions.
[0412] There is a compelling need to develop a method for
depositing MgB.sub.2 thin films that produces crystalline,
conformal deposits below 400.degree. C. via an in situ deposition
process, without the need for subsequent annealing at elevated
temperatures. To date, only the co-evaporation method comes close
to this requirement, but this method cannot afford conformal films
on topologically complex substrates. A CVD method to MgB.sub.2
films would be far more useful. It is known that metal borohydrides
such as Zr(BH.sub.4).sub.4, Hf(BH.sub.4).sub.4, and
Cr(B.sub.3H.sub.8).sub.2 are excellent CVD precursors for MB.sub.2
thin films at temperatures as low as 150.degree. C..sup.15-17 The
structure of MgB.sub.2 is identical with that of these transition
metal diborides, but no low-temperature CVD methods for depositing
MgB.sub.2 thin films have been described, largely due to the
absence of suitable precursors. To address this lack, we report
herein the synthesis of highly volatile magnesium hydroborate
complexes, Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.sup.18 and
Mg(B.sub.3H.sub.8).sub.2L.sub.2 (L=Et.sub.2O or Me.sub.2O)..sup.19
Initial attempts to use the latter molecules as precursors for the
CVD of MgB.sub.2 afforded boron-rich non-stoichiometric films,
principally because the onset temperatures for deposition were high
(.gtoreq.400.degree. C.), thus leading to significant evaporative
loss of Mg during growth.
[0413] We now describe the successful chemical vapor deposition of
doped MgB.sub.2 phases from the precursor
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 at lower temperatures by
conducting the depositions in the presence of a catalyst that
accelerates the surface reaction rate of the MgB.sub.2 precursor.
The phases are doped because metal atoms from the catalyst are
partly incorporated into the films by substitution into the Mg
sites. We find that several molecules can serve as effective
catalysts for the CVD growth of the doped MgB.sub.2 phase, of which
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is the most attractive so far
because it leads to the lowest level of Mg site substitution. This
is the first successful low-temperature CVD method for the
deposition of doped MgB.sub.2 thin films. The doping levels are
high enough to render the films non-superconducting above 4 K, but
the results described herein clearly point the way to the
development of technologically-attractive CVD processes to grow
superconducting MgB.sub.2 thin films at temperatures below
400.degree. C.
Results and Discussion
[0414] Catalyzed Chemical Vapor Deposition of
Mg.sub.0.8Ti.sub.0.2B.sub.2.
[0415] Bis(N,N-dimethyl-diboranamido)magnesium(II),
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, is highly volatile; its vapor
pressure of 800 mTorr at 20.degree. C..sup.18 is the highest among
all known magnesium compounds. When gaseous
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is passed over heated
substrates in vacuum, no deposition occurs up to 500.degree. C.,
except for the formation of traces of magnesium oxide, which
results from reactions of the precursor with background water in
the chamber. Interestingly, bulk
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 begins to decompose at
120.degree. C. with evolution of gas..sup.18 We did not explore
deposition temperatures above 500 0, owing to the known propensity
of MgB.sub.2 to undergo magnesium loss above 400.degree. C..sup.11
The low reactivity of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 at
surface temperatures below 500.degree. C. suggests that there is a
kinetic barrier associated with the nucleation and growth from this
precursor. If so, then it might be possible to induce growth under
these conditions by adding a suitable growth catalyst.
[0416] We have found that addition of small amounts of the titanium
compound Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 to the
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 precursor flux results in the
deposition of a titanium-doped MgB.sub.2 phase on Si(100) at
temperatures as low as 250.degree. C. The ratio between the partial
pressures of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 in the growth stream was
approximately 10. The best films were grown between 300 and
400.degree. C.; below 250.degree. C. the films contain .about.10%
carbon, and at 600.degree. C. the films are significantly depleted
in magnesium (.about.3 at. %).
[0417] At 350.degree. C., simultaneous passage of
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and 10% of
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 over a Si(100) substrate
affords silvery, mirror-bright deposits. Identical results were
obtained on SiO.sub.2 and sapphire substrates. The AES depth
profiles (FIG. 17) reveal that the boron to metal ratio, B/(Mg+Ti),
is very close to 2, and that the Mg to Ti ratio is approximately 3.
Negligible amounts of carbon (<2%) and nitrogen (<1%) are
present. Because lighter elements can often be preferentially
sputtered out during the collection of AES depth profiles, the film
stoichiometry was assessed independently by a non-destructive
technique, Rutherford backscattering spectroscopy (RBS). Well
separated Mg and Ti peaks are seen, with the Mg peak overlapping
partly with the tail of the silicon substrate signal (FIG. 18). The
Mg to Ti ratio from the RBS data is 4; consequently, we conclude
that the film stoichiometry is Mg.sub.0.8Ti.sub.0.2B.sub.2.
[0418] X-ray photoelectron spectra (XPS) of the deposits grown on
Si(100) at 350.degree. C. show that significant amounts of oxygen
are present on the surface of the films due to the air-oxidation
during the sample transport from the growth chamber to the XPS
chamber. Upon sputtering surface layers away, the oxides signals
become negligible (FIG. 19). An XPS spectrum obtained after
sputtering into the interior of the film exhibited a Mg 2p binding
energy of 50.65 eV (FIG. 20); this value lies between the reported
values .about.49.5 and .about.51.3 eV for bulk and thin films of
MgB.sub.2, respectively..sup.20-23 The Mg 2p binding energy of our
films may be affected by the presence of titanium. The B 1s peak of
188.1 eV lies in the observed range of 186.55 eV-188.2 eV for
MgB.sub.2..sup.20-23 The Ti 2p binding energy of 454.8 eV is close
to the value of 454.3 eV observed for TiB.sub.2..sup.24,25 XPS
signal for N 1s and C.sub.1s were near background levels.
[0419] The X-ray diffraction (XRD) profile shows that the films are
polycrystalline, and that the lattice parameters are those of a
MB.sub.2 phase (FIG. 21). The cell constants (a=3.056 and c=3.432
.ANG.) differ slightly from those for bulk MgB.sub.2, and lie
between those for pure MgB.sub.2 (a=3.086 and c=3.522 .ANG.) and
for pure TiB.sub.2 (a=3.03 and c=3.23 .ANG.). The cell parameters
more closely resemble those of pure MgB.sub.2 (FIG. 22), as
expected from the Mg.sub.0.8Ti.sub.0.2B.sub.2 stoichiometry. No
preferential orientation of the crystallites is noted on the
Si(100) substrate. Magnesium-depleted films grown at 450 and
600.degree. C. are non-crystalline.
[0420] Scanning electron micrographs of fracture cross-sections
show that the films are essentially columnar (FIG. 23), which is a
consequence of the low surface diffusion rates of the adatoms at
the 350.degree. C. growth temperature. For similar reasons, a
columnar growth morphology has been seen for HfB.sub.2 films grown
from Hf(BH.sub.4).sub.4 at 400.degree. C..sup.16 Transmission
electron micrographs of the Mg.sub.0.8Ti.sub.0.2B.sub.2 films
confirm the columnar growth morphology and reveal the presence of
polycrystals with non-uniform orientations (FIG. 24).
[0421] Electron energy loss spectroscopy (EELS) shows that the
titanium atoms are homogeneously distributed throughout the
deposits (the B/Mg/Ti ratios are the same in all locations). The
formation of a homogeneously mixed material and the absence of
segregation into separate MgB.sub.2 and TiB.sub.2 phases can be
ascribed to slow diffusion rates of metal atoms at the low
deposition temperature of 350.degree. C.
[0422] The electrical resistivity of the crystalline
Mg.sub.0.8Ti.sub.0.2B.sub.2 films on sapphire gradually decreases
upon cooling from room temperature to 4 K, but no superconducting
transition was observed. The absence of a superconducting
transition strongly suggests that titanium substitutes into the
magnesium sites in the MgB.sub.2 phase (see below).
[0423] Dependence of the Properties of Mg.sub.1-xTi.sub.xB.sub.2 on
the Film Microstructure.
[0424] Our results differ from another study of the effect of
adding TiB.sub.2 to MgB.sub.2..sup.26-29 Specifically, Zhao et al.
have reported that the solid state reaction of magnesium, boron,
and titanium powders at 900.degree. C. affords a material composed
of 90% MgB.sub.2 and 10% TiB.sub.2 that has a critical current
density about 10 times greater than that of pure MgB.sub.2.
Interestingly, samples prepared by mixing 40% MgB.sub.2 with 60%
TiB.sub.2 still exhibited a superconducting transition..sup.26 The
authors ascribed the high critical current density to improvements
in intergranular contacts between MgB.sub.2 grains, and to strong
vortex pinning by a second phase (probably TiB.sub.2), rather than
to the replacement of Ti for Mg in the MgB.sub.2 phase.
[0425] The absence of a superconducting transition for our
CVD-deposited Mg.sub.0.8Ti.sub.0.2B.sub.2 films can be ascribed to
the direct substitution of Ti for Mg atoms in the MB.sub.2 lattice;
our samples are not intimate mixtures of largely separate TiB.sub.2
and MgB.sub.2 phases as in the study by Zhao et al. It is known
that replacement of Mg with Al,.sup.30 Sc,.sup.31, Mn,.sup.32,33
Co,.sup.34 and Cu.sup.35 leads to a drop in the superconducting
transition temperature. Similar drops in the critical temperature
are also seen when carbon is substituted into the boron
sites..sup.36,37 The addition of enough electrons to MgB.sub.2 by
substitutional replacement moves the Fermi level to a lower density
of state region where superconductivity disappears.
[0426] Another factor that can disrupt the superconducting
transition in our mixed Mg.sub.0.8Ti.sub.0.2B.sub.2 films is the
magnetic moment of the titanium atoms. Exchange interactions
between conduction electrons and the magnetic moments of
substituted ions are known to weaken Cooper pairing and to suppress
superconductivity..sup.38 This effect is sufficiently large that
replacing only 2% of the Mg atoms in MgB.sub.2 with Mn renders the
material non-superconductive..sup.33 It is therefore not surprising
that our Mg.sub.0.8Ti.sub.0.2B.sub.2 films, in which 20% of Mg
sites are substituted by Ti, are not superconducting.
[0427] Static Vacuum Deposition and Analyses of the Gaseous
Byproducts.
[0428] In order to investigate the chemical mechanism by which the
Mg.sub.0.8Ti.sub.0.2B.sub.2 films are deposited from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2, we have analyzed the gaseous
byproducts that are generated during deposition. Under a static
vacuum (0.05 Torr), Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 were sublimed into a deposition
zone maintained at 300.degree. C. After the deposition was
complete, the gaseous byproducts were collected, dissolved in
C.sub.6D.sub.6, and analyzed by .sup.1H and .sup.13C NMR
spectroscopy. The principal byproducts are H.sub.2 and
[Me.sub.2NBH.sub.2].sub.2. The formation of
[Me.sub.2NBH.sub.2].sub.2 from amino-borane compounds is known to
be catalyzed by certain transition-metal compounds..sup.39-43 These
findings suggests that the mass balance for the deposition of
MgB.sub.2 is
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2-.fwdarw.MgB.sub.2+[Me.sub.2NBH.sub.2]-
.sub.2+H.sub.2.
[0429] Survey of Other Potential Catalysts for the Deposition of
MgB.sub.2 from Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
[0430] We have shown above that the deposition of thin films by CVD
can be catalyzed by addition of small amounts of a co-reactant.
Specifically, Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 by itself does
not afford any deposits even at temperatures as high as 500.degree.
C. In contrast, addition of small amounts of
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 results in the deposition of
Mg-containing thin films at temperatures as low as 300.degree.
C.
[0431] We conducted a survey to determine whether other compounds
could catalyze the growth of thin films from the
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 precursor; we were particularly
interested in discovering catalysts that would generate undoped
(and thus superconducting) MgB.sub.2 thin films. The results are
summarized in Table 1; all the depositions were conducted at
350.degree. C. The hydroborate complexes Ti(BH.sub.4).sub.3(dme),
Zr(BH.sub.4).sub.4, Hf(BH.sub.4).sub.4, and
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2 all can serve as catalysts, but
all afford deposits in which the transition metal substitutes for
some of the Mg atoms, and films of approximate composition
Mg.sub.0.8M.sub.0.2B.sub.2. The yttrium complex
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) also catalyzes the growth
of Mg-containing deposits, but the film stoichiometry is
approximately Mg.sub.0.45Y.sub.0.55B.sub.3.5 and no MgB.sub.2 phase
is present as shown by XRD. The deposits obtained from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 in the presence of the
transition metal complexes Ti(NMe.sub.2).sub.4, CpPd(allyl), and
Fe(CO).sub.5 all contain significant amounts of carbon, but no
MB.sub.2 phase. Other compounds tested--including the titanium
alkyl Ti(neo-pentyl).sub.4, the metallocene
Ni(C.sub.5H.sub.4Me).sub.2, and the halo compounds ethyl iodide and
iodine--were unable to initiate the film growth.
[0432] Few examples of catalyzed CVD growth have been described.
Transition metal catalysts have been shown to lower the deposition
temperature,.sup.45,46 initiate the film growth,.sup.47 or
facilitate the removal of the ligands from the
precursors..sup.48,49 For example, Puddephatt and co-workers
reported that the deposition of yttrium oxide from Y(thd).sub.3
(thd=2,2,6,6-tetramethyl-3,5-heptanedionate) and oxygen could be
significantly accelerated by the presence of small amounts of a
palladium catalyst..sup.46 The palladium content in the deposited
film was nearly undetectable by XPS. They proposed that the
palladium migrates through Y.sub.2O.sub.3 as Pd(thd).sub.2, which
is generated from the reaction of metallic palladium with the CVD
reaction product Hthd. We believe that the idea of catalyzing CVD
reactions constitutes a fascinating new direction for CVD
research.
Experimental Section
[0433] General Methods.
[0434] .sup.1H NMR spectra were recorded on a Varian Unity 400
instrument at 400 MHz. Chemical shifts are reported in .delta.
units (positive shifts to high frequency) relative to
tetramethylsilane. A HP 6980 Series gas chromatograph equipped with
a 30 m AT.TM.-WAX (polyethylene glycol, 0.25 mm i.d., Alltech)
column and a HP 5973 mass selective detector was used to obtain the
GC/MS data. Auger spectra were recorded on a Physical Electronics
PHI 660 system with a beam energy of 5 kV and a base pressure of
ca. 1.times.10.sup.-10 Torr. X-ray photoelectron spectra were
recorded on a Physical Electronics PHI 5400 system with a 15 kV,
300 W Mg K.alpha. radiation source (1253.6 eV). AES and XPS spectra
were collected after the samples had been argon-sputtered to remove
contaminants on the surface. X-ray diffraction data were recorded
on a Phillips Xpert system with Cu K.alpha. radiation. Scanning
electron micrographs were recorded on a Hitachi S4700 instrument.
Rutherford back scattering data were recorded on 3-MeV Van de
Graaff accelerator. Electrical resistivities were measured by the
four-point probe method..sup.50
[0435] Reagents.
[0436] Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2,.sup.18
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf),.sup.18
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2,.sup.51
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2,.sup.51
Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6,.sup.52
CpPd(allyl),.sup.53 Ti(neo-pentyl).sub.4,.sup.54
Ti(BH.sub.4).sub.3(dme),.sup.55 Cu(hfac)(VTMS),.sup.56
Zr(BH.sub.4).sub.4, and Hf(BH.sub.4).sub.4.sup.57 were prepared as
described in the literature. Ethyl iodide, iodine, methylhydrazine,
Ni(C.sub.5H.sub.4Me).sub.2, Fe(CO).sub.5, and Ti(NMe.sub.2).sub.4
were purchased from Aldrich and used without further
purification.
[0437] CVD of Mg.sub.1-xTi.sub.xB.sub.2.
[0438] Deposition of thin films was carried out in an ultra high
vacuum (UHV) chamber equipped with a turbomolecular pump; the base
pressure was 5.times.10.sup.-9 Torr..sup.58 The reactants were
delivered to the film growth surface without the use of a carrier
gas. The stainless steel reservoir was kept at room temperature for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2,
Cp*Mg(H.sub.3BNMe.sub.2BH.sub.3)(thf), CpPd(allyl),
Ti(neo-pentyl).sub.4, Cu(hfac)(VTMS), Ni(C.sub.5H.sub.4Me).sub.2,
Fe(CO).sub.5, ethyl iodide, iodine, and methylhydrazine. The
reservoir was kept at 30.degree. C. for
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2,
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2, and Ti(BH.sub.4).sub.3(dme);
at 100.degree. C. for Y.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6; and
at -5.degree. C. for Zr(BH.sub.4).sub.4 and Hf(BH.sub.4).sub.4. The
fluxes of highly volatile ethyl iodide, methylhydrazine,
Fe(CO).sub.5, Zr(BH.sub.4).sub.4 and Hf(BH.sub.4).sub.4 were
regulated by a needle valve. Reactants were delivered to the growth
surface through two independent 0.25 inch (6.35 mm) o.d. stainless
steel tubes, one for the MgB.sub.2 source and one for the other
co-reactant. The line pressure of the
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 precursor was maintained at
120-150 mTorr during the growth run. The silicon substrates were
degreased by successive sonications in acetone,
tetrachloroethylene, isopropanol, and deionized water for 10 min
each. To remove the native oxide on the surface, the degreased
silicon substrates were immersed in a 10% HF solution and then
rinsed with deionized water. Silicon substrates were heated by
passing an electric current through the substrate, and the surface
temperature was determined by means of an infrared pyrometer. An in
situ spectroscopic ellipsometer was used to monitor the film
thickness in real time. The magnesium atomic density was calculated
by dividing the magnesium areal density (determined by RBS) by the
film thickness (measured by SEM).
[0439] Analysis of Byproducts of CVD Growth.
[0440] To collect and analyze the gaseous products from the
reaction of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 with
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 under the CVD conditions, CVD
experiments was carried out in a closed static vacuum system. Two
small glass vials that contain Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
and Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 separately were placed in a
standard Schlenk (250 mL) tube, the middle of which was wrapped
with an electric heating tape (Thermolyne Briskheat). The apparatus
was evacuated to 0.05 Torr and the electric heating tape was heated
up to 300.degree. C., forming a deposition hot zone. The stopcock
between the apparatus and the vacuum pump was closed during the
deposition. After the deposition was complete, the gaseous
byproducts were analyzed by GC/MS and by NMR methods (the gaseous
products were condensed in a liquid N.sub.2 cooled NMR tube). A
similar apparatus has been described..sup.59 The principal
byproducts are H.sub.2 (singlet at .delta. 4.46) and
[Me.sub.2NBH.sub.2].sub.2 (.sup.1H NMR: .delta. 3.06 (1:1:1:1
quartet, J.sub.BH=110 Hz, BH.sub.2) .delta. 2.22 (s, NMe.sub.2).
.sup.13C{.sup.1H}NMR: .delta. 52.0 (s, NMe.sub.2). The chemical
shifts and the splitting patterns for [Me.sub.2NBH.sub.2].sub.2 in
C.sub.6D.sub.6 are consistent with those reported..sup.43,60 GC-MS
analysis of the byproducts shows that dimethylamine is the only
detectable species. Boron-containing products are not seen in the
GC-MS assay suggests because they react with the polyethylene
glycol stationary phase.
REFERENCES
[0441] 1. Abelson, L. A.; Kerber, G. L. P. IEEE. 2004, 92,
1517-1533. [0442] 2. Brock, D. K.; Track, E. K.; Rowell, J. M. IEEE
Spectrum 2000, 37, 40-46. [0443] 3. Chen, W.; Rylyakov, A. V.;
Patel, V.; Lukens, J. E.; Likharev, K. K. Appl. Supercon. IEEE
Trans. 1999, 9, 3212-3215. [0444] 4. Likharev, K. K.; Semenov, V.
K. Appl. Supercon. IEEE Trans. 1991, 1, 3-28. [0445] 5. Tonouchi,
M.; Fujimaki, A.; Tanabe, K.; Enpuku, K.; Nikawa, K.; Kobayashi, T.
Jpn. J. Appl. Phys. 1 2005, 44, 7735-7749. [0446] 6. Klein, N. Rep.
Prog. Phys. 2002, 65, 1387-1425. [0447] 7. Claeson, T.; Ivanov, Z.;
Winkler, D. Curr. Opin. Solid St. M. 1999, 4, 45-52. [0448] 8.
Nagamatsu, J.; Nakagawa, N.; Muranaka, T.; Zenitani, Y.; Akimitsu,
J. Nature 2001, 410, 63-64. [0449] 9. Xu, M.; Kitazawa, H.; Takano,
Y.; Ye, J.; Nishida, K.; Abe, H.; Matsushita, A.; Tsujii, N.; Kido,
G. Appl. Phys. Lett. 2001, 79, 2779-2781. [0450] 10. Tsuda, S.;
Yokoya, T.; Kiss, T.; Takano, Y.; Togano, K.; Kito, H.; Ihara, H.;
Shin, S. Phys. Rev. Lett. 2001, 8717. [0451] 11. Fan, Z. Y.; Hinks,
D. G.; Newman, N.; Rowell, J. M. Appl. Phys. Lett. 2001, 79, 87-89.
[0452] 12. Kang, W. N.; Kim, H. J.; Choi, E. M.; Jung, C. U.; Lee,
S. L. Science 2001, 292, 1521-1523. [0453] 13. Ueda, K.; Naito, M.
J. Appl. Phys. 2003, 93, 2113-2120. [0454] 14. Zeng, X. H.;
Pogrebnyakov, A. V.; Kotcharov, A.; Jones, J. E.; Xi, X. X.;
Lysczek, E. M.; Redwing, J. M.; Xu, S. Y.; Lettieri, J.; Schlom, D.
G.; Tian, W.; Pan, X. Q.; Liu, Z. K. Nat. Mater. 2002, 1, 35-38.
[0455] 15. Sung, J. W.; Goedde, D. M.; Girolami, G. S.; Abelson, J.
R. J. Appl. Phys. 2002, 91, 3904-3911. [0456] 16. Jayaraman, S.;
Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson, J. R. J. Vac. Sci.
Technol., A 2005, 23, 1619-1625. [0457] 17. Jayaraman, S.; Klein,
E. J.; Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson, J. R. J.
Vac. Sci. Technol., A 2005, 23, 631-633. [0458] 18. See Example 13.
[0459] 19. See Example 12. [0460] 20. Ueda, K.; Yamamoto, H.;
Naito, M. Physica C 2002, 378, 225-228. [0461] 21. Talapatra, A.;
Bandyopadhyay, S. K.; Sen, P.; Barat, P.; Mukherjee, S.; Mukherjee,
M. Physica C 2005, 419, 141-147. [0462] 22. Garg, K. B.; Chatterji,
T.; Dalela, S.; Heinormen, M.; Leiro, J.; Dalela, B.; Singhal, R.
K. Solid State Commun. 2004, 131, 343-347. [0463] 23. Vasquez, R.
P.; Jung, C. U.; Park, M. S.; Kim, H. J.; Kim, J. Y.; Lee, S. I.
Phys. Rev. B 2001, 6405. [0464] 24. Aouadi, S. M.; Debessai, M.;
Namavar, E.; Wong, K. C.; Mitchell, K. A. R. Surf. Coat. Technol.
2004, 183, 369-377. [0465] 25. Baker, M. A.; Steiner, A.; Haupt,
J.; Gissler, W. J. Vac. Sci. Technol., A 1995, 13, 1633-1638.
[0466] 26. Zhao, Y.; Feng, Y.; Cheng, C. H.; Zhou, L.; Wu, Y.;
Machi, T.; Fudamoto, Y.; Koshizuka, N.; Murakami, M. Appl. Phys.
Lett. 2001, 79, 1154-1156. [0467] 27. Wilke, R. H. T.; Bud'ko, S.
L.; Canfield, P. C.; Kramer, M. J.; Wu, Y. Q.; Finnemore, D. K.;
Suplinskas, R. J.; Marzik, J. V.; Hannahs, S. T. Physica C 2005,
418, 160-167. [0468] 28. Wang, J.; Bugoslaysky, Y.; Berenov, A.;
Cowey, L.; Caplin, A. D.; Cohen, L. F.; Driscoll, J. L. M.; Cooley,
L. D.; Song, X.; Larbalestier, D. C. Appl. Phys. Lett. 2002, 81,
2026-2028. [0469] 29. Kitaguchi, H.; Matsumoto, A.; Kumakura, H.;
Doi, T.; Yamamoto, H.; Saitoh, K.; Sosiati, H.; Hata, S. Appl.
Phys. Lett. 2004, 85, 2842-2844. [0470] 30. Slusky, J. S.; Rogado,
N.; Regan, K. A.; Hayward, M. A.; Khalifah, P.; He, T.; Inumaru,
K.; Loureiro, S. M.; Haas, M. K.; Zandbergen, H. W.; Cava, R. J.
Nature 2001, 410, 343-345. [0471] 31. Agrestini, S.; Metallo, C.;
Filippi, M.; Simonelli, L.; Campi, G.; Sanipoli, C.; Liarokapis,
E.; De Negri, S.; Giovannini, M.; Saccone, A.; Latini, A.;
Bianconi, A. Phys. Rev. B 2004, 70. [0472] 32. Xu, S.; Moritomo,
Y.; Kato, K.; Nakamura, A. J. Phys. Soc. Jpn. 2001, 70, 1889-1891.
[0473] 33. Rogacki, K.; Batlogg, B.; Karpinski, J.; Zhigadlo, N.
D.; Schuck, G.; Kazakov, S. M.; Wagli, P.; Puzniak, R.; Wisniewski,
A.; Carbone, F.; Brinkman, A.; van der Marel, D. Phy. Rev. B
(Condensed Matter and Materials Physics) 2006, 73, 174520-8. [0474]
34. Kuhberger, M.; Gritzner, G. Physica C 2002, 370, 39-43. [0475]
35. Tampieri, A.; Celotti, G.; Sprio, S.; Rinaldi, D.; Barucca, G.;
Caciuffo, R. Solid State Commun. 2002, 121, 497-500. [0476] 36. de
la Pena, O.; Aguayo, A.; de Coss, R. Phys. Rev. B 2002, 66, 012511.
[0477] 37. Klie, R. F.; Zheng, J. C.; Zhu, Y.; Zambano, A. J.;
Cooley, L. D. Phys. Rev. B (Condensed Matter and Materials Physics)
2006, 73, 014513-10. [0478] 38. Moca, C. P.; Horea, C. Phys. Rev. B
2002, 66, 052501. [0479] 39. Clark, T. J.; Russell, C. A.; Manners,
I. J. Am. Chem. Soc. 2006, 128, 9582-9583. [0480] 40. Jaska, C. A.;
Manners, I. J. Am. Chem. Soc. 2004, 126, 1334-1335. [0481] 41.
Jaska, C. A.; Manners, I. J. Am. Chem. Soc. 2004, 126, 9776-9785.
[0482] 42. Jaska, C. A.; Temple, K.; Lough, A. J.; Manners, I. J.
Am. Chem. Soc. 2003, 125, 9424-9434. [0483] 43. Jaska, C. A.;
Temple, K.; Lough, A. J.; Manners, I. Chem. Commun. 2001, 962-963.
[0484] 44. Shim, K. C.; Lee, H. B.; Kwon, O. K.; Park, H. S.; Koh,
W.; Kang, S. W. J. Electrochem. Soc. 2002, 149, G109-G113. [0485]
45. Zhang, Y.; Choi, S. W. K.; Puddephatt, R. J. J. Am. Chem. Soc.
1997, 119, 9295-9296. [0486] 46. Zhang, Y.; Puddephatt, R. J. Chem.
Mater. 1999, 11, 148-153. [0487] 47. R. H. W. Au, R. J. P. Chem.
Vap. Deposition 2007, 13, 20-22. [0488] 48. Alfred Zinn, B. N. H.
D. K. Adv. Mater. 1992, 4, 375-378. [0489] 49. Niemer, B.; Zinn, A.
A.; Stovall, W. K.; Gee, P. E.; Hicks, R. F.; Kaesz, H. D. Appl.
Phys. Lett. 1992, 61, 1793-1795. [0490] 50. Schroder, D. K.
Semiconductor Materials and Device Characterization, 2nd Ed.;
Wiley-Interscience 1998. [0491] 51. See Example 13. [0492] 52. See
Example 14. [0493] 53. Tatsuno, Y.; Yoshida, T.; Otsuka, S. Inorg.
Synth. 1979, 19, 220-3. [0494] 54. Girolami, G. S.; Jensen, J. A.;
Pollina, D. M.; Williams, W. S.; Kaloyeros, A. E.; Allocca, C. M.
J. Am. Chem. Soc. 1987, 109, 1579-1580. [0495] 55. Jensen, J. A.;
Girolami, G. S. Inorg. Chem. 1989, 28, 2107-2113. [0496] 56. Chi,
K. M.; Shin, H. K.; Hampden-Smith, M. J.; Kodas, T. T. Inorg.
Synth. 1997, 31, 289-294. [0497] 57. Goedde, D. M. Ph.D. Thesis,
University of Illinois at Urbana-Champaign, 2001. [0498] 58. For
the details of the growth condition, see: J., Sreenivas; Yang, Y.;
Kim, D. Y.; Girolami, G. S.; Abelson, J. R. J. Vac. Sci. Technol.,
A 2005, 23, 1619-1625. [0499] 59. Jeffries, P. M.; Dubois, L. H.;
Girolami, G. S. Chem. Mater. 1992, 4, 1169-1175. [0500] 60.
Srivastava, D. K.; Krannich, L. K.; Watkins, C. L. Inorg. Chem.
1991, 30, 2441-2444.
Example 16
Chemical Vapor Deposition of Metal Oxide Thin films from Metal
N,N,-Dimethlydiboranamide Compounds and Water
Introduction
[0501] Metal oxides have many interesting applications including
High-T.sub.c superconductors, ion conductors, dielectrics in
microelectronics, optical widows, passive and protective layers.
Chemical vapor deposition is an important method to grow metal
oxide thin films, which usually involves the reaction of metal
containing precursors, including metal halides, alkyls, alkoxides,
beta-diketonates, and sometimes alkylaminate, with oxygen sources
such as water and O.sub.2. In this example, we show the first time
that metal oxide films can be deposited from borohdride-bonded
precursors. The deposition of MgO for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is of particular interest and
is therefore reported in details, because it is superior to any
other CVD processes in that it affords high quality, rapid growing
and conformal MgO films at low deposition temperatures.
[0502] MgO is a refractory oxide with a melting point of
2852.degree. C. It has a relative dielectrics constant of 9.8. It's
optically transparent to a wide spectrum due to its large band gap
(7.2 eV). Its low sputtering rate and high second electron emission
coefficient make it a suitable protective material in plasma
display panels,.sup.1,2 MgO has a NaCl type crystal structure and
has a lattice constant of 4.211 .ANG.. It is closely
lattice-matched to a range of materials including the high Tc
superconductor oxide.sup.3, ferroelectric oxide.sup.4,5, conductive
transparent oxide .sup.6, metals .sup.7-10 and metal
nitrides.sup.11-13, therefore Single crystal MgO has been the
choice of substrate for the epitaxial growth of these materials. In
addition, MgO thin films has been used as buffer layers for
eptaixial and highly oriented overgrowth of them on single crystal
silicon.sup.14-18, GaAs.sup.19-21, sapphire.sup.22, and glass
.sup.23 substrates. The epitaxial MgO has also been used as an
insulation layer for the magnetoresistance junction.sup.25,26.
[0503] MgO thin films can be deposited by PVD and CVD methods.
Comparing to PVD the advantages of CVD include the simplicity of
the process and the high growth conformality, however, it also have
disadvantages such as high growth temperature, relatively high
impurity level, and limited growth rate. Unfortunately, so far the
reported CVD growths of MgO did not fully demonstrate their
advantages but suffered a great deal from disadvantages: The growth
rates are usually only a few nm/min; growth temperature above
400.degree. C. is required; impurities like carbon and halogen has
been detected. Such issues can be attributed to the Mg containing
precursors being used for deposition. In Table 1 we summarized the
Mg precursors that have been employed for CVD growth of MgO. These
precursors generally have very low vapor pressure, and have to be
delivered with the assistance of a carrier gas at an elevated
temperature. The low precursor feeding rate limits the film growth
rate. Most of these precursors use oxygen as a co-reactant and the
ligands attached to Mg are removed by complete oxidation, leaving
issues such as high reaction temperature and impurity level.
[0504] We have developed a completely new type of Mg precursor,
bis(dimethyldiboranamido)magnesium
(Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2). The structure and
preparation of this precursor is reported herein. The vapor
pressure of this precursor is .about.0.8 Torr at room temperature,
which is more than an order of magnitude higher that those listed
in Table 1. The precursor is thermally stable. However, when
supplied with water, it produces MgO films at temperatures as low
as 225.degree. C. The high vapor pressure of the precursor can
either allow us to achieve extremely conformal growth, or film
growth at a rate of a few hundred nm/min. Below we report the CVD
growth kinetics, the microstructure, crystallinity, electric and
optical properties of the MgO films for
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and H.sub.2O.
Experiment
[0505] The vapor pressure of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
was measured using a similar method as described in ref [28]. The
precursor container is directly connected to a capacitance
manometer. After the vapor is pumped into vacuum, the pressure rise
as a function of time is recorded, as shown in FIG. 25. The vapor
pressure of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 at 30.degree. C. is
0.82 Torr. The high vapor pressure of this precursor allows it to
flow into the growth chamber with considerable feed rate without
any carrier gas. During growth, both H.sub.2O and
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 were maintained at room
temperature and were conducted to the chamber through a 1/4'' O.D.
stainless steel tube. Their partial pressure in the chamber was
controlled by regulating the corresponding inline metering valves.
A steady state partial pressure as high as 10.sup.-2 Torr could be
established for Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
[0506] The CVD growth has been carried out in an UHV chamber with
base pressure of 5.times.10.sup.-9 Torr which has been described in
detail elsewhere [29]. The substrates used for this work are
Si(100) and Corning 7059 glass. Both substrates were degreased
thoroughly with organic solvents before being loaded into the
growth chamber. The silicon substrates were dipped into 10% HF
solution for 10 seconds to remove native oxide. The silicon
substrates were heated directly by passing current though, whereas
the glass substrates were heated indirectly by a backed conductive
silicon piece. A k-type thermocouple was placed onto the substrate
for temperature measurement.
[0507] In-situ SE studies were carried out with a J. A. Woollam
M-2000FI.TM. rotating compensator system with its accompanying
software EASE.TM.. The incident angle was fixed at 70.degree.. The
photon energies used for SE measurements spanned from the infra-red
to the ultra-violet (0.75-5.05 eV). For dynamic studies of growth,
a spectroscopic scan was acquired every 2-10 seconds. A standard
multilayer model is employed to describe the MgO film, which
consists of a substrate layer (silicon or glass) and a dielectric
film layer simulated by a Cauchy model.
[0508] Film thickness and microstructure were determined by
examining the fracture cross-sections in a scanning electron
microscope (SEM). Film stoichiometry was measured by Auger electron
spectrometer (AES) and Rutherford backscattering spectrometry
(RBS). RBS also measured the area density of the Mg atom in the
film, which was used to calculate the film density. The surface
morphology of the film was studied by atomic force microscopy
(AFM). The film crystallinity was analyzed by X-ray diffraction
(Rigaku DMAX). For electrical characterization, a gold film was
evaporated onto MgO/Si and the C-V and I-V measurements were
carried out on this MOS structure. Optical transmission of the film
grown on glass substrates were measured by a UV-VIS-NIR
spectrophotometer (Varian Cary 5 G).
Results and Discussions
Growth Kinetics
[0509] The spectroscopic ellipsometer has a very high precision and
sensitivity in the MgO film thickness measurement. Film thickness
values are in very good agreement with the value measured by SEM,
whereas film thickness change in angstrom level can be detected.
The spectrometer was able to acquire a full spectrum scan in less
than a second, thus a powerful tool to monitor the film growth rate
in real-time.
[0510] FIG. 26 shows the MgO film growth rate as a function of
substrate temperature with a Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2
pressure of 2.times.10.sup.-5 Torr and H.sub.2O pressure of
3.times.10.sup.-5 Torr at substrate temperature ranging from
275.degree. C. to 800.degree. C. At 275.degree. C.
<T<400.degree. C., the growth rapidly increases with T, which
is a clear indication of reaction-limited growth. However, at
T.gtoreq.400.degree. C. the growth rate decreases with temperature,
inconsistent with the conventional knowledge of a flux-limited
growth where the growth rate is supposed to be invariant of
temperature. There are two possible reasons for this growth rate
decreasing. First, the growth is carried out in a cold wall
reactor, and the sample is the only heat source. At higher growth
temperature, the surface surrounding the sample will be heated
substantially, reaching a temperature above the CVD growth
threshold, which is .about.250.degree. C. in this case. Therefore,
at a constant feed rate growth condition, these hot surface acts as
a sink to the precursor and reduces the precursor partial pressure
inside the chamber, which in turn decreases the growth rate on the
substrate. Clearly, the higher the substrate temperature is, the
larger this effect. We have observed similar growth rate reduction
at higher growth temperature for the HfB.sub.2 CVD growth in the
same reactor.[29] The reaction rate drop at higher growth
temperatures is also possibly due to the decrease of the hydroxyl
group density on the surface which reduces the sticking coefficient
of the metal containing precursor, as suggested by Matero et al. in
their study of the ALD growth of Al.sub.2O.sub.3.[30]
[0511] FIG. 27a presents a higher resolution study of the reaction
limited regime. In this experiment the substrate temperature was
ramped up linearly with a rate of 0.05.degree. C./sec, with the
film thickness monitored in real-time. The growth rate as a
function of temperature was obtained by taking the first derivative
of the thickness profile, and was shown in an Arrhenius plot. (FIG.
27a) The flux and reaction limited growth regimes are clearly
separated. The apparent activation energy calculated from the slope
of the plot at the reaction limited regime is 151 kJ/mol. Note that
this energy is an apparent value for the reaction mechanism
containing multiple reaction steps. It is likely to correspond to
the activation energy of the rate limiting step; however, under a
different precursor pressure the competition among various reaction
steps may lead to a different value.
[0512] The growth rate as a function of Mg precursor pressure is
presented in FIG. 27b. The water pressure was kept at 3 mTorr,
which is significantly higher than the Mg pressure. The growth rate
saturates at high Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 pressure,
which could be attributed to a "site-blocking" mechanism: the
surface sites are all occupied by the precursor molecules that have
not complete the surface reaction, and thus is unavailable to the
incoming precursor molecules. The consequence is that the reaction
probability decreases as precursor pressure increases. The growth
at this regime is highly desired for coating of complex features,
because lower precursor reaction probability leads to better growth
conformality [31]. FIG. 28a shows an example of an ultra-conformal
MgO film grown on a deep trench structure with depth to width ratio
equal to 30:1. In this growth experiment, the substrate temperature
was 225.degree. C., and the Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
H.sub.2O pressures were 6 mTorr and 15 mTorr, respectively. The
film growth rate was 2 nm/min, and the reaction probability of the
precursor is calculated to be 6.times.10.sup.-5, which in theory is
capable of coating a 50:1 aspect ratio trench according to
simulation study.[31] Note that for CVD growth with more than one
reactant, the grown conformality is limited by the reactant with
lowest process pressure, in this case
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2.
[0513] The growth conformality shown in FIG. 28a is comparable to
that of atomic layer deposition (ALD). However, ALD suffers from
its low growth rate, whereas CVD has the possibility of trading off
the conformality with growth rate by varying the deposition
conditions, demonstrated by the MgO growth shown in FIGS. 28b and
28c. Here, a higher substrate temperature of 285.degree. C. was
used to enhance the growth rate by an order of magnitude, while
still maintaining excellent growth conformality on lower aspect
ratio trenches. The growth rate could be further boosted up to
hundreds of nm/min with a requirement on conformality. The growths
with high growth rate or high conformality require high precursor
pressures, therefore the capability of this CVD MgO process is
attributed to the unique high vapor pressure of the
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 precursor.
Film Stoichiometry
[0514] The composition of the MgO films grown at various
temperatures are characterized by AES, as shown FIG. 29. The
impurities may be expected from the precursor molecules including
carbon, boron, and nitrogen. The intensity of these elements are
essentially below the instrument detection limit for all the films
being characterized, except the one grown at 400.degree. C. which
contains a few percent of boron. The atomic concentration in the
Auger electron spectroscopy are calculated from the standard
sensitivity factors provided by the software, therefore the
consistent magnesium to oxygen ratio of 4:3 found by AES, as shown
in FIG. 29, may not correspond to the actually film stoichiometry.
To obtain a more accurate film stoichiometry, RBS was employed to
measure the number per area of the magnesium and oxygen atoms in
the film. A typical RBS spectrum of a film grown at 500.degree. C.
is shown in FIG. 30, where the Mg to 0 ratio is 0.9:1. While the
MgO films deposited at most other temperatures has similar Mg to 0
ratio, the 400.degree. C. film has Mg/0=0.7. The higher oxygen
content in all the CVD MgO films could be explained by an
incomplete decomposition or a post-growth adsorption of water into
the film, given that the alkaline-earth metal oxide has a strong
affinity to water. Excessive oxygen content due to water adsorption
is reported in an ALD growth of Y.sub.2O.sub.3 thin film [32].
[0515] From atomic density per area measurement by RBS, we could
further calculate the atomic density per volume of the film by
dividing the atomic density per area with the film thickness. The
Mg density of our films are mostly 80-90% of that of a perfect MgO
crystal, except that the film grown at 400.degree. C. has a lower
density of 70%. Such film density values are reasonable considering
that most of our films are amorphous or weakly crystallized.
Clearly, the film grown at 400.degree. C. has poorer quality than
those grown at lower or higher temperatures.
Film Surface Morphology, Microstructure and Crystallinity
[0516] The cross sectional SEM images of the MgO films grown at
275.degree. C., 400.degree. C., and 600.degree. C. with a
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 pressure of 2.times.10.sup.-5
Torr and H.sub.2O pressure of 3.times.10.sup.-5 Torr are shown in
FIG. 31. The film grown at high temperatures are clearly columnar,
owing to the high reaction probability of the precursor. Films
grown at T<300.degree. C. are very smooth, even at a large
thickness (FIG. 28b). X-ray diffraction spectra (FIG. 32) suggest
that the film start to crystallize at 500.degree. C. The x-ray peak
is sharper at higher growth temperature, indicating an increased
crystallinity with growth temperature. Films grown on Si(100)
substrate at all growth temperatures are universally (002)
textured, partially attributed to a registration with the substrate
symmetry. However, a film grown on glass substrate at 700.degree.
C. also shows (002) texture, indicating that (002) texture is
inherently favored, agreed with reported MgO growth by CVD [33,
34].
Optical and Electrical Properties
[0517] By modeling the ellipsometry spectrum with Cauchy equation,
the refractive index of the MgO film grown at 275.degree. C. and
600.degree. C. as a function of wavelength are shown in FIG. 33a.
The refractive index of bulk MgO, is present in the same figure for
comparison. The CVD MgO films have a slightly smaller refractive
index, which could be explained by their lower density comparing
with bulk MgO. Both films have excellent transparency. As shown in
the transmittance spectrum (FIG. 33b), the 250 nm thick films grown
at both 275.degree. C. and 600.degree. C. on glass substrates have
a transmittance >90% in spectrum ranging from near UV to near
IR. The dielectric constant of the MgO film grown on Si substrate
is 9.5 by a C-V measurement, slightly lower than the bulk MgO value
of 9.8, which could also be attributed to the film density.
CVD of Other Metal Oxide Thin Films
[0518] Y.sub.2O.sub.3 and TiO.sub.2 are the other two metal oxide
thin films that have been successfully deposited from the
corresponding diboronaminde compound
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3 and
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 precursors using water as a
co-reactant. Both of them are also very useful materials.
Y.sub.2O.sub.3 has a high permittivity, and thus is a candidate for
the high .kappa. gate dielectric material for next generation
microelectronics [32]. It has a very small lattice mismatch with Si
and can serve as an epitaxial buffer layer for ferroelectrics and
superconductor oxides [35]. TiO.sub.2 is known to be a good
photo-catalyst [36].
[0519] FIG. 34 shows the AES depth profiling of the TiO.sub.2 and
Y.sub.2O.sub.3 thin films deposited from the diboranamide
precursors. Similar to the AES analysis of MgO film, the oxygen to
metal ratio does not exactly match with the bulk material
stoichiometry, which can also be explain by the inappropriate use
of the standard AES sensitivity factors for the oxide films.
However, carbon, nitrogen, and boron levels are below the AES
detection limit, indicating that the films are free of impurities.
The films are dense, but columnar, similar to the MgO film
deposited at low pressure. The vapor pressure of
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3 are much lower than
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2, thus only low precursor
pressure can be used. This explains the columnar microstructure of
the films, as shown in FIG. 35. It is very similar to the MgO film
deposited at low pressure conditions (FIG. 31). FIG. 36 shows the
XRD profile of a Y.sub.2O.sub.3 film deposited at 800.degree. C. on
a Si(100) substrate, which is actually an unsuccessful epitaxial
growth attempt. In spite of the close lattice match between Si(100)
and Y.sub.2O.sub.3(100), the film is strongly (111) textured. This
is because at high temperature, silicon tends to react with the
oxygen source (H.sub.2O here) to form an amorphous SiO.sub.2 film
on top, which blocks the direct contact of the crystalline silicon
with the oxide film. The texture observed in FIG. 31 is in fact a
film texture formed on silicon oxide. The epitaxial growth of oxide
on silicon substrate should be carried out at conditions where
SiO.sub.2 formation is not preferred or the oxygen source is
strictly controlled [37], both of which are not trivial for simple
thermal CVD.
[0520] Besides their vapor pressure, one other important difference
between
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3/Ti(H.sub.3BNMe.sub.2BH.sub.3).-
sub.2 and Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 is that the former
generally decompose at T>300.degree. C. as single source
precursors. The thermal decomposition of
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 has been described herein, and
Y(H.sub.3BNMe.sub.2BH.sub.3).sub.3 has a similar behavior. The
afforded films contain significant amount of metal, boron, carbon,
and nitrogen. Therefore, in the oxide growth if the water supply is
insufficient, it should be expected that the boron, carbon, and
nitrogen level in the film will be elevated. However, as shown in
FIG. 37, one growth of Y.sub.2O.sub.3 with lower water pressure
only shows boron as the impurity. This result is interesting and
actually provides us with some hint to the growth mechanism. There
decomposition of the diboranamide ligand may involve two steps. The
fraction containing dimethylamino group, which is likely to be
converted to the stable molecule bis-p-(dimethylamino)-diborane
(H.sub.2B=NMe.sub.2) leaves the surface earlier than the other
borohydride group.
Summary
[0521] We demonstrate a simple CVD route toward high quality MgO,
TiO.sub.2 and Y.sub.2O.sub.3 films from the dimethyldiboranamide
precursors and H.sub.2O. Compared to the reported CVD of MgO, our
methods has the merit of low deposition temperature
(.gtoreq.225.degree. C.), excellent conformality (conformally
coated a 35:1 trench), and high growth rate (>100 nm/min), which
is mainly attributed to their remarkable volatility (Pv=0.82 mTorr
at 30.degree. C.) of Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 and its
high reactivity with H.sub.2O. The growth rate increases with
temperature, while it saturates under high
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 pressure At low growth
temperatures (<300.degree. C.), indicating a Langmurian surface
reaction mechanism. The film crystallizes at T>500.degree. C.
with a (002) texture on (100) oriented single crystal silicon and
glass substrates. Films grown at T>400.degree. C. are columnar,
whereas the films grown a lower temperatures are dense and smooth.
The refractive index of the film is 1.69-1.72 and the dielectric
constant is 9.5, both of which are very close to bulk MgO. The
combination of the high process capability and excellent film
quality makes the CVD growth of MgO from
Mg(H.sub.3BNMe.sub.2BH.sub.3).sub.2 very attractive for a variety
of technical applications.
REFERENCES
[0522] [1] G. Auday, P. Guillot, J. Galy, J. Appl. Phys. 88 (2000)
4871. [0523] [2] J. P. Boeuf, J. of Phys. D-Applied Physics 36
(2003) R53. [0524] [3] R. Ramesh, et al., Appl. Phys. Lett. 56
(1990) 2243. [0525] [4] Y. Gao, G. Bai, K. L. Merkle, Y. Shi, H. L.
M. Chang, Z. Shen, D. J. Lam, J. of Mater. Res. 8 (1993) 145.
[0526] [5] C. M. Foster, et al., J. Appl. Phys. 78 (1995) 2607.
[0527] [6] M. Yan, M. Lane, C. R. Kannewurf, R. P. H. Chang, Appl.
Phys. Lett. 78 (2001) 2342. [0528] [7] B. M. Lairson, M. R.
Visokay, R. Sinclair, B. M. Clemens, Appl. Phys. Lett. 62 (1993)
639. [0529] [8] J. W. He, P. J. Moller, Surf. Sci. 178 (1986) 934.
[0530] [9] B. M. Lairson, M. R. Visokay, R. Sinclair, S. Hagstrom,
B. M. Clemens, Appl. Phys. Lett. 61 (1992) 1390. [0531] [10] P.
Sandstrom, E. B. Svedberg, J. Birch, J. E. Sundgren, J. Cryst.
Growth 197 (1999) 849. [0532] [11] K. Inumaru, T. Ohara, S.
Yamanaka, Appl. Surf. Sci. 158 (2000) 375. [0533] [12] C. S. Shin,
S. Rudenja, D. Gall, N. Hellgren, T. Y. Lee, I. Petrov, J. E.
Greene, J. Appl. Phys. 95 (2004) 356. [0534] [13] H. S. Seo, T. Y.
Lee, I. Petrov, J. E. Greene, D. Gall, J. Appl. Phys. 97 (2005).
[0535] [14] B. S. Kwak, E. P. Boyd, K. Zhang, A. Erbil, B. Wilkins,
Appl. Phys. Lett. 54 (1989) [0536] 2542. [0537] [15] B. H. Moeckly,
S. E. Russek, D. K. Lathrop, R. A. Buhrman, J. Li, J. W. Mayer,
Appl. Phys. Lett. 57 (1990) 1687. [0538] [16] M. M. Sung, C. Kim,
C. G. Kim, Y. Kim, J. Cryst. Growth 210 (2000) 651. [0539] [17] F.
Niu, B. H. Hoerman, B. W. Wessels, J. Vac. Sci. Technol. B 18
(2000) 2146. [0540] [18] A. K. Sharma, A. Kvit, J. Narayan, J. Vac.
Sci. Technol. A 17 (1999) 3393. [0541] [19] L. S. Hung, L. R.
Zheng, T. N. Blanton, Appl. Phys. Lett. 60 (1992) 3129. [0542] [20]
K. Nashimoto, D. K. Fork, T. H. Geballe, Appl. Phys. Lett. 60
(1992) 1199. [0543] [21] J. Musolf, E. Boeke, E. Waffenschmidt, X.
He, M. Heuken, K. Heime, J Alloy Compd 195 (1993) 295. [0544] [22]
W. I. Park, D. H. Kim, G. C. Yi, C. Kim, Jpn. J. Appl. Phys. 41
(2002) 6919. [0545] [23] L. A. Wang, Y. Yang, S. Jin, T. J. Marks,
Appl. Phys. Lett. 88 (2006). [0546] [24] M. Bauer, R. Semerad, H.
Kinder, leee Transactions on Applied Superconductivity 9 (1999)
1502. [0547] [25] J. Mathon, A. Umerski, Phys. Rev. B 6322 (2001).
[0548] [26] S. Yuasa, A. Fukushima, T. Nagahama, K. Ando, Y.
Suzuki, Japan. J. of Appl. Phys. Part 2-Letters & Express
Letters 43 (2004) L588. [0549] [27] D. Y. Kim, G. S. Girolami, see
herein. [0550] [28] T. Ohta, F. Cicoira, P. Doppelt, L. Beitone, P.
Hofmann, Chem. Vapor Depos. 7 (2001) 33. [0551] [29] S. Jayaraman,
Y. Yang, D. Y. Kim, G. S. Girolami, J. R. Abelson, J. Vac. Sci.
Technol. A 23 (2005) 1619. [0552] [30] R. Matero, A. Rahtu, M.
Ritala, M. Leskela, T. Sajavaara, Thin Solid Films 368 (2000) 1
[0553] [31] Y. Yang, J. R. Abelson, See herein. [0554] [32] P. de
Rouffignac, J. S. Park, R. G. Gordon, Chem. Mater. 17 (2005) 4808.
[0555] [33] L. Wang, Y. Yang, J. Ni, C. L. Stern, T. J. Marks,
Chem. Mater. 17 (2005) 5697. [0556] [34] M. M. Sung, C. G. Kim, J.
Kim, Y. Kim, Chem. Mater. 14 (2002) 826. [0557] [35] S. C. Choi, M.
H. Cho, S. W. Whangbo, C. N. Whang, S. B. Kang, S. I. Lee, M. Y.
Lee, Appl. Phys. Lett. 71 (1997) 903. [0558] [36] A. Mills, N.
Elliott, I. P. Parkin, S. A. O'Neill, R. J. Clark, J. of Photochem.
and Photobio. a 151 (2002) 171. [0559] [37] J. Lettieri, J. H.
Haeni, D. G. Schlom, J. Vac. Sci. Technol. A 20 (2002) 1332. [0560]
[38] Y. W. Zhao, H. Suhr, Appl. Phys. A-Materials Science &
Processing 54 (1992) 451. [0561] [39] Z. Lu, R. S. Feigelson, R. K.
Route, S. A. Dicarolis, R. Hiskes, R. D. Jacowitz, J. Cryst. Growth
128 (1993) 788. [0562] [40] E. Fujii, A. Tomozawa, S. Fujii, H.
Torii, R. Takayama, T. Hirao, Jpn. J. Appl. Phys. 33 (1994) 6331.
[0563] [41] J. H. Boo, K. S. Yu, W. Koh, Y. Kim, Mater. Lett. 26
(1996) 233. [0564] [42] J. M. Zeng, H. Wang, S. X. Shang, Z. Wang,
M. Wang, J. Cryst. Growth 169 (1996) 474. [0565] [43] J. H. Boo, S.
B. Lee, K. S. Yu, W. Koh, Y. Kim, Thin Solid Films 341 (1999) 63.
[0566] [44] E. Fujii, A. Tomozawa, H. Torii, R. Takayama, M.
Nagaki, T. Narusawa, Thin Solid Films 352 (1999) 85. [0567] [45] T.
Hatanpaa, J. Ihanus, J. Kansikas, I. Mutikainen, M. Ritala, M.
Leskela, Chem. Mater. 11 (1999) 1846. [0568] [46] J. S. Matthews,
O. Just, B. Obi-Johnson, W. S. Rees, Chem. Vapor Depos. 6 (2000)
129. [0569] [47] W. Fan, P. R. Markworth, T. J. Marks, R. P. H.
Chang, Mater. Chem. Phys. 70 (2001) 191. [0570] [48] J. R. Babcock,
D. D. Benson, A. G. Wang, N. L. Edleman, J. A. Belot, M. V. Metz,
T. J. Marks, Chem. Vapor Depos. 6 (2000) 180. [0571] [49] R. Huang,
A. H. Kitai, Appl. Phys. Lett. 61 (1992) 1450. [0572] [50] R.
Huang, A. H. Kitai, J. of Elec. Mater. 22 (1993) 215. [0573] [51]
M. Putkonen, T. Sajavaara, L. Niinisto, J. Mater. Chem. 10 (2000)
1857. [0574] [52] M. Putkonen, M. Nieminen, L. Niinisto, Thin Solid
Films 466 (2004) 103.
Example 12
TABLE-US-00001 [0575] TABLE 1 2 3 Formula
MgB.sub.6C.sub.8H.sub.36O.sub.2 MgB.sub.6C.sub.4H.sub.28O.sub.2
formula weight 253.54 197.43 T, .degree. C. -80 -80 space group
P2.sub.12.sub.12 Pca2.sub.1 a, .ANG. 7.337(4) 13.9644(19) b, .ANG.
15.586(8) 6.9088(10) c, .ANG. 8.332(4) 16.034(2) V, .ANG..sup.3
952.7(9) 1546.9(4) Z 2 4 .rho..sub.calcd, g cm.sup.-3 0.884 0.848
.lamda., .ANG. 0.71073 0.71073 .mu..sub.calcd, cm.sup.-1 0.81 0.86
transmissn coeff 0.956-0.966 0.954-0.991 unique reflns 1750 2837
Parameters 151 186 R.sub.1.sup.a 0.0726 0.0347 wR.sub.2.sup.b
0.1579 0.0796 .sup.aR.sub.1 = .SIGMA.| |F.sub.o| - |F.sub.c|
|/.SIGMA.|F.sub.o| for reflections with F.sub.o.sup.2 > 2
.sigma.(F.sub.o.sup.2). .sup.bwR.sub.2 = [.SIGMA.w(F.sub.o.sup.2 -
F.sub.c.sup.2).sup.2/.SIGMA. w(F.sub.o.sup.2).sup.2].sup.1/2 for
all reflections.
Example 12
TABLE-US-00002 [0576] TABLE 2 Bond Lengths (.ANG.) Mg--O 2.025(3)
Mg--B(1) 2.575(5) Mg--B(2) 2.591(5) Mg--H(11) 1.99(3) Mg--H(21)
2.01(4) B(1)--B(2) 1.779(7) B(1)--B(3) 1.795(10) B(2)--B(3)
1.809(7) B(1)--H(11) 1.17(2) B(1)--H(12) 1.12(3) B(1)--H(13)
1.02(4) B(2)--H(21) 1.17(2) B(2)--H(22) 1.11(3) B(2)--H(23) 1.02(4)
B(3)--H(13) 1.43(4) B(3)--H(23) 1.43(4) B(3)--H(31) 1.02(3)
B(3)--H(32) 1.02(3) Bond Angles (deg) O'--Mg--O 93.66(16)
O'--Mg--H(11) 92.9(8) O--Mg--H(11) 172.8(9) O'--Mg--H(21) 100.8(10)
O--Mg--H(21) 85.8(8) H(11)--Mg--H(21) 90.0(15) B(2)--B(1)--B(3)
60.8(3) B(2)--B(1)--Mg 70.3(2) B(3)--B(1)--Mg 105.2(3)
B(2)--B(1)--H(11) 116.7(15) B(3)--B(1)--H(11) 117.5(15)
Mg--B(1)--H(11) 48.1(15) B(2)--B(1)--H(12) 114(2) B(3)--B(1)--H(12)
133(2) Mg--B(1)--H(12) 116(2) H(11)--B(1)--H(12) 106(3)
B(2)--B(1)--H(13) 113(2) B(3)--B(1)--H(13) .sup. 53(2)
Mg--B(1)--H(13) 127(4) H(11)--B(1)--H(13) .sup. 96(4)
H(12)--B(1)--H(13) 109(4) B(1)--B(2)--B(3) 60.0(3) B(1)--B(2)--Mg
69.4(2) B(3)--B(2)--Mg 104.2(3) B(1)--B(2)--H(21) 117(2)
B(3)--B(2)--H(21) 121.7(18) Mg--B(2)--H(21) .sup. 48(2)
B(1)--B(2)--H(22) 112(2) B(3)--B(2)--H(22) 126(2) Mg--B(2)--H(22)
123(2) H(21)--B(2)--H(22) 109(3) B(1)--B(2)--H(23) 112(2)
B(3)--B(2)--H(23) .sup. 52(2) Mg--B(2)--H(23) 126(3)
H(21)--B(2)--H(23) .sup. 99(3) H(22)--B(2)--H(23) 107(4)
B(1)--B(3)--B(2) 59.2(3) B(1)--B(3)--H(13) 34.6(18)
B(2)--B(3)--H(13) 93.8(19) B(1)--B(3)--H(23) 93.5(18)
B(2)--B(3)--H(23) 34.3(17) H(13)--B(3)--H(23) 128(4)
B(1)--B(3)--H(31) 107(3) B(2)--B(3)--H(31) 113(3)
H(13)--B(3)--H(31) .sup. 96(4) H(23)--B(3)--H(31) 106(4)
B(1)--B(3)--H(32) 111(3) B(2)--B(3)--H(32) 118(3)
H(13)--B(3)--H(32) .sup. 96(4) H(23)--B(3)--H(32) 107(3)
H(31)--B(3)--H(32) 127(4) H(21)--B(2)--H(23) .sup. 99(3)
Example 12
TABLE-US-00003 [0577] TABLE 3 Bond Lengths (.ANG.) Mg(1)--O(2)
2.0181(15) Mg(1)--O(1) 2.0279(14) Mg(1)--B(2) 2.557(3) Mg(1)--B(4)
2.559(3) Mg(1)--B(1) 2.570(3) Mg(1)--B(5) 2.572(3) Mg(1)--H(11)
1.967(19) Mg(1)--H(21) 1.973(16) Mg(1)--H(41) 1.91(2) Mg(1)--H(51)
1.98(2) B(1)--B(2) 1.795(4) B(1)--B(3) 1.802(4) B(2)--B(3) 1.803(5)
B(4)--B(5) 1.777(4) B(4)--B(6) 1.804(5) B(5)--B(6) 1.780(4)
B(1)--H(11) 1.140(19) B(1)--H(12) 1.13(2) B(1)--H(13) 1.10(2)
B(2)--H(21) 1.167(19) B(2)--H(22) 1.144(19) B(2)--H(23) 1.11(2)
B(3)--H(13) 1.38(2) B(3)--H(23) 1.45(2) B(3)--H(31) 1.06(2)
B(3)--H(32) 1.06(2) B(4)--H(41) 1.19(2) B(4)--H(42) 1.08(2)
B(4)--H(43) 1.17(3) B(5)--H(51) 1.14(2) B(5)--H(52) 1.10(2)
B(5)--H(53) 1.15(2) B(6)--H(43) 1.45(2) B(6)--H(53) 1.39(2)
B(6)--H(61) 1.11(2) B(6)--H(62) 1.17(2) Bond Angles (deg)
O(2)--Mg(1)--O(1) 91.80(6) O(2)--Mg(1)--H(11) 172.8(6)
O(1)--Mg(1)--H(11) 90.3(6) B(2)--Mg(1)--H(11) 65.3(6)
B(4)--Mg(1)--H(11) 90.2(6) B(1)--Mg(1)--H(11) 24.8(6)
B(5)--Mg(1)--H(11) 94.8(6) O(2)--Mg(1)--H(21) 83.2(6)
O(1)--Mg(1)--H(21) 91.9(5) B(2)--Mg(1)--H(21) 26.0(6)
B(4)--Mg(1)--H(21) 158.2(5) B(1)--Mg(1)--H(21) 66.4(6)
B(5)--Mg(1)--H(21) 117.8(5) H(11)--Mg(1)--H(21) 89.9(8)
O(2)--Mg(1)--H(41) 106.2(6) O(1)--Mg(1)--H(41) 85.8(7)
B(2)--Mg(1)--H(41) 145.6(6) B(4)--Mg(1)--H(41) 25.9(7)
B(1)--Mg(1)--H(41) 104.7(6) B(5)--Mg(1)--H(41) 65.8(7)
H(11)--Mg(1)--H(41) 80.8(8) H(21)--Mg(1)--H(41) 170.3(8)
O(2)--Mg(1)--H(51) 89.1(5) O(1)--Mg(1)--H(51) 174.6(6)
B(2)--Mg(1)--H(51) 85.0(6) B(4)--Mg(1)--H(51) 64.6(6)
B(1)--Mg(1)--H(51) 83.4(6) B(5)--Mg(1)--H(51) 24.9(6)
H(11)--Mg(1)--H(51) 89.4(8) H(21)--Mg(1)--H(51) 93.6(8)
H(41)--Mg(1)--H(51) 88.8(9) B(2)--B(1)--B(3) 60.15(18)
B(2)--B(1)--H(11) 114.4(9) B(3)--B(1)--H(11) 120.9(10)
Mg(1)--B(1)--H(11) 46.5(9) B(2)--B(1)--H(12) 110.3(10)
B(3)--B(1)--H(12) 125.7(11) Mg(1)--B(1)--H(12) 120.8(12)
H(11)--B(1)--H(12) 111.5(14) B(2)--B(1)--H(13) 110.2(12)
B(3)--B(1)--H(13) 50.0(12) Mg(1)--B(1)--H(13) 127.5(12)
H(11)--B(1)--H(13) 101.1(15) H(12)--B(1)--H(13) 108.8(17)
B(1)--B(2)--B(3) 60.14(17) B(1)--B(2)--Mg(1) 69.90(13)
B(3)--B(2)--Mg(1) 106.10(17) B(1)--B(2)--H(21) 116.3(8)
B(3)--B(2)--H(21) 120.5(9) Mg(1)--B(2)--H(21) 47.8(8)
B(1)--B(2)--H(22) 110.4(9) B(3)--B(2)--H(22) 123.1(10)
Mg(1)--B(2)--H(22) 123.4(10) H(21)--B(2)--H(22) 113.4(12)
B(1)--B(2)--H(23) 113.7(12) B(3)--B(2)--H(23) 53.6(12)
Mg(1)--B(2)--H(23) 127.7(12) H(21)--B(2)--H(23) 97.1(15)
H(22)--B(2)--H(23) 104.7(15) B(1)--B(3)--B(2) 59.72(16)
B(1)--B(3)--H(13) 37.5(10) B(2)--B(3)--H(13) 97.2(11)
B(1)--B(3)--H(23) 97.6(10) B(2)--B(3)--H(23) 37.9(10)
H(13)--B(3)--H(23) 135.1(15) B(1)--B(3)--H(31) 117.5(12)
B(2)--B(3)--H(31) 116.5(11) H(13)--B(3)--H(31) 102.5(16)
H(23)--B(3)--H(31) 100.7(15) B(1)--B(3)--H(32) 116.5(12)
B(2)--B(3)--H(32) 115.2(12) H(13)--B(3)--H(32) 102.1(15)
H(23)--B(3)--H(32) 99.9(15) H(31)--B(3)--H(32) 118.2(17)
B(5)--B(4)--B(6) 59.60(17) B(5)--B(4)--H(41) 113.4(10)
B(6)--B(4)--H(41) 120.2(9) Mg(1)--B(4)--H(41) 44.6(10)
B(5)--B(4)--H(42) 114.7(12) B(6)--B(4)--H(42) 129.4(13)
Mg(1)--B(4)--H(42) 118.9(13) H(41)--B(4)--H(42) 108.1(16)
B(5)--B(4)--H(43) 113.0(13) B(6)--B(4)--H(43) 53.4(12)
Mg(1)--B(4)--H(43) 129.4(13) H(41)--B(4)--H(43) 101.0(16)
H(42)--B(4)--H(43) 105.5(19) B(4)--B(5)--B(6) 60.97(18)
B(4)--B(5)--Mg(1) 69.35(12) B(6)--B(5)--Mg(1) 106.48(17)
B(4)--B(5)--H(51) 114.7(10) B(6)--B(5)--H(51) 118.4(10)
Mg(1)--B(5)--H(51) 47.3(10) B(4)--B(5)--H(52) 110.4(12)
B(6)--B(5)--H(52) 127.3(12) Mg(1)--B(5)--H(52) 118.7(12)
H(51)--B(5)--H(52) 112.1(15) B(4)--B(5)--H(53) 112.4(11)
B(6)--B(5)--H(53) 51.5(11) Mg(1)--B(5)--H(53) 129.1(12)
H(51)--B(5)--H(53) 98.4(15) H(52)--B(5)--H(53) 108.2(16)
B(5)--B(6)--B(4) 59.43(17) B(5)--B(6)--H(43) 99.6(11)
B(4)--B(6)--H(43) 40.2(11) B(5)--B(6)--H(53) 40.3(10)
B(4)--B(6)--H(53) 99.8(10) H(43)--B(6)--H(53) 139.9(15)
B(5)--B(6)--H(61) 116.2(10) B(4)--B(6)--H(61) 118.2(11)
H(43)--B(6)--H(61) 103.3(14) H(53)--B(6)--H(61) 99.4(13)
B(5)--B(6)--H(62) 119.3(11) B(4)--B(6)--H(62) 119.3(11)
H(43)--B(6)--H(62) 100.1(15) H(53)--B(6)--H(62) 100.3(15)
H(61)--B(6)--H(62) 113.9(15)
Example 13
TABLE-US-00004 [0578] TABLE 1 1 2 3 4 formula
C.sub.4H.sub.24B.sub.4N.sub.2Mg C.sub.8H.sub.32B.sub.4N.sub.2OMg
C.sub.8H.sub.34B.sub.4N.sub.2O.sub.2Mg C.sub.16H.sub.35B.sub.2NOMg
formula weight 167.80 239.91 257.92 303.38 T, .degree. C. -80 -80
-80 -80 space group I 42d Cc C2/c P2.sub.1/n a, .ANG. 11.3649(19)
10.0103(8) 22.5822(17) 11.309(3) b, .ANG. 11.3649(19) 17.5686(15)
13.6560(10) 14.569(3) c, .ANG. 19.183(7) 10.5611(8) 14.700(2)
12.255(3) .beta., deg 90 111.412(5) 125.324(3) 90.397(X) V,
.ANG..sup.3 2477.6(10) 1729.2(2) 3698.6(7) 2019.1(8) Z 8 4 8 4
.rho..sub.calcd, g cm.sup.-3 0.900 0.922 0.926 0.998 .lamda., .ANG.
0.71073 0.71073 0.71073 0.71073 .mu..sub.calcd, cm.sup.-1 0.94 0.87
0.88 0.86 transmissn coeff 0.963-0.979 0.982-0.994 0.970-0.989
0.985-0.997 unique reflns 1542 2576 3840 3827 parameters 161 197
268 222 R.sub.1.sup.a 0.0297 0.0455 0.0349 0.0679 wR.sub.2.sup.b
0.0688 0.1196 0.0883 0.1393 .sup.aR1 = .SIGMA.| |F.sub.o| -
|F.sub.c| |/.SIGMA.|F.sub.o| for reflections with F.sub.o.sup.2
> 2 .sigma.(F.sub.o.sup.2). .sup.bwR.sub.2 =
[.SIGMA.w(F.sub.o.sup.2 - F.sub.c.sup.2).sup.2/.SIGMA.
w(F.sub.o.sup.2).sup.2].sup.1/2 for all reflections.
Example 13
TABLE-US-00005 [0579] TABLE 2 Bond Lengths (.ANG.) Mg(1)--H(11)
1.990(15) Mg(1)--H(12) 2.021(11) Mg(1)--H(21) 2.058(16)
Mg(1)--H(22) 1.998(15) Mg(1)--B(1) 2.3690(14) Mg(1)--B(2)
2.3859(13) B(1)--H(11) 1.126(15) B(1)--H(12) 1.151(13) B(1)--H(13)
1.033(16) B(2)--H(21) 1.110(16) B(2)--H(22) 1.166(18) B(2)--H(23)
1.072(12) B(1)--N(1) 1.5847(13) B(2)--N(2) 1.5810(13) N(1)--C(1)
1.4884(15) N(2)--C(2) 1.4869(14) Bond Angles (deg)
H(11)--Mg(1)--H(12) 54.1(6) H(11)--Mg(1)--H(21) 86.2(6)
H(11)--Mg(1)--H(22) 91.8(7) H(12)--Mg(1)--H(21) 92.6(5)
H(12)--Mg(1)--H(22) 135.6(6) H(21)--Mg(1)--H(22) 53.6(6)
B(1)--Mg(1)--B(1)' 66.55(6) B(1)--Mg(1)--B(2) 119.96(5)
B(1)--Mg(1)--B(2)' 155.05(6) B(2)--Mg(1)--B(2)' 65.53(6)
H(11)--B(1)--H(12) 106.5(10) H(11)--B(1)--H(13) 113.5(13)
H(12)--B(1)--H(13) 110.3(12) H(21)--B(2)--H(22) 107.0(10)
H(21)--B(2)--H(23) 111.0(13) H(22)--B(2)--H(23) 111.1(11)
N(1)--B(1)--Mg(1) 91.63(7) N(2)--B(2)--Mg(1) 92.48(6)
B(1)--N(1)--B(1)' 110.20(11) B(2)--N(2)--B(2)' 109.52(11)
C(1)--N(1)--B(1) 109.52(9) C(1)--N(1)--B(1)' 109.36(9)
C(2)--N(2)--B(2) 109.80(9) C(2)--N(2)--B(2)' 109.62(10)
C(1)'--N(1)--C(1) 108.85(16) C(2)--N(2)--C(2)' 108.47(13)
N(1)--B(1)--H(11) 106.1(8) N(1)--B(1)--H(12) 106.7(7)
N(1)--B(1)--H(13) 113.3(8) N(2)--B(2)--H(21) 106.6(8)
N(2)--B(2)--H(22) 107.6(7) N(2)--B(2)--H(23) 113.2(6) .sup.a
Symmetry transformations used to generate equivalent atoms: ' = x,
-y + 1/2, -z + 1/4
Example 13
TABLE-US-00006 [0580] TABLE 3 Bond Lengths (.ANG.) Mg(1)--H(11)
2.14(3) Mg(1)--H(12) 2.10(3) Mg(1)--H(21) 2.29(6) Mg(1)--H(22)
1.98(4) Mg(1)--H(31) 2.20(3) Mg(1)--H(32) 2.11(3) Mg(1)--H(41)
2.28(3) Mg(1)--H(42) 1.94(3) Mg(1)--B(1) 2.487(4) Mg(1)--B(2)
2.553(5) Mg(1)--B(3) 2.484(4) Mg(1)--B(4) 2.503(4) Mg(1)--O(1)
2.063(2) B(1)--H(11) 1.09(3) B(1)--H(12) 1.11(3) B(1)--H(13)
1.12(3) B(2)--H(21) 1.14(3) B(2)--H(22) 1.08(3) B(2)--H(23) 1.15(3)
B(3)--H(31) 1.12(2) B(3)--H(32) 1.06(3) B(3)--H(33) 1.06(3)
B(4)--H(41) 1.13(2) B(4)--H(42) 1.16(3) B(4)--H(43) 1.07(3)
B(1)--N(1) 1.565(5) B(2)--N(1) 1.532(6) B(3)--N(2) 1.576(5)
B(4)--N(2) 1.562(4) N(1)--C(1) 1.460(4) N(1)--C(2) 1.479(4)
N(2)--C(3) 1.477(4) N(2)--C(4) 1.483(4) Bond Angles (deg)
H(11)--Mg(1)--H(12) 49.7(11) H(11)--Mg(1)--H(21) 58.5(16)
H(11)--Mg(1)--H(22) 89.6(12) H(11)--Mg(1)--H(31) 92.3(11)
H(11)--Mg(1)--H(32) 140.4(10) H(11)--Mg(1)--H(41) 65.3(11)
H(11)--Mg(1)--H(42) 103.8(12) H(12)--Mg(1)--H(21) 86.0(15)
H(12)--Mg(1)--H(22) 81.0(14) H(12)--Mg(1)--H(31) 141.9(10)
H(12)--Mg(1)--H(32) 169.9(11) H(12)--Mg(1)--H(41) 96.1(11)
H(12)--Mg(1)--H(42) 98.6(13) H(21)--Mg(1)--H(22) 46.0(13)
H(21)--Mg(1)--H(31) 68.2(13) H(21)--Mg(1)--H(32) 99.8(16)
H(21)--Mg(1)--H(41) 101.6(13) H(21)--Mg(1)--H(42) 151.7(13)
H(22)--Mg(1)--H(31) 98.4(13) H(22)--Mg(1)--H(32) 97.0(13)
H(22)--Mg(1)--H(41) 147.5(10) H(22)--Mg(1)--H(42) 162.2(12)
H(31)--Mg(1)--H(32) 48.1(10) H(31)--Mg(1)--H(41) 64.3(11)
H(31)--Mg(1)--H(42) 92.7(12) H(32)--Mg(1)--H(41) 90.9(11)
H(32)--Mg(1)--H(42) 80.2(13) H(41)--Mg(1)--H(42) 50.3(11)
B(1)--Mg(1)--B(2) 59.91(16) B(1)--Mg(1)--B(4) 106.80(13)
B(3)--Mg(1)--B(1) 141.87(15) B(3)--Mg(1)--B(2) 111.21(19)
B(3)--Mg(1)--B(4) 61.62(12) B(4)--Mg(1)--B(2) 151.0(2)
O(1)--Mg(1)--B(1) 110.65(12) O(1)--Mg(1)--B(2) 103.2(2)
O(1)--Mg(1)--B(3) 107.48(13) O(1)--Mg(1)--B(4) 105.79(12)
H(11)--B(1)--H(12) 109(2) H(11)--B(1)--H(13) 114(3)
H(12)--B(1)--H(13) 104(3) H(21)--B(2)--H(22) .sup. 99(3)
H(21)--B(2)--H(23) 118(4) H(22)--B(2)--H(23) 107(3)
H(31)--B(3)--H(32) 107(2) H(31)--B(3)--H(33) 109(2)
H(32)--B(3)--H(33) 102(2) H(41)--B(4)--H(42) 105(2)
H(41)--B(4)--H(43) 112(2) H(42)--B(4)--H(43) 114(2)
N(2)--B(4)--Mg(1) 94.25(19) N(1)--B(1)--Mg(1) 96.0(2)
N(1)--B(2)--Mg(1) 94.3(3) N(2)--B(3)--Mg(1) 94.6(2)
B(2)--N(1)--B(1) 108.8(3) B(4)--N(2)--B(3) 109.0(2)
C(1)--N(1)--B(1) 110.0(3) C(1)--N(1)--B(2) 114.4(5)
C(2)--N(1)--B(1) 110.1(3) C(2)--N(1)--B(2) 107.5(4)
C(3)--N(2)--B(3) 110.1(3) C(3)--N(2)--B(4) 109.7(3)
C(4)--N(2)--B(3) 109.5(2) C(1)--N(1)--C(2) 106.0(3)
C(3)--N(2)--C(4) 108.3(3) C(4)--N(2)--B(4) 110.3(3)
N(1)--B(1)--H(11) 106.9(17) N(1)--B(1)--H(12) 107.6(17)
N(1)--B(1)--H(13) 116(2) N(1)--B(2)--H(21) 100(3) N(1)--B(2)--H(22)
119(2) N(1)--B(2)--H(23) 113(2) N(2)--B(3)--H(31) 107.4(15)
N(2)--B(3)--H(32) 114.7(18) N(2)--B(3)--H(33) 116.4(16)
N(2)--B(4)--H(41) 104.5(16) N(2)--B(4)--H(42) 110.0(17)
N(2)--B(4)--H(43) 110.5(16)
Example 13
TABLE-US-00007 [0581] TABLE 4 Bond Lengths (.ANG.) Mg(1)--H(11)
1.984(13) Mg(1)--H(21) 2.010(13) Mg(1)--H(31) 2.119(13)
Mg(1)--H(32) 2.395(13) Mg(1)--H(41) 2.157(14) Mg(1)--H(42)
2.199(13) Mg(1)--B(1) 2.6077(18) Mg(1)--B(2) 2.8680(19) Mg(1)--B(3)
2.6333(18) Mg(1)--B(4) 2.5621(18) Mg(1)--O(1) 2.1118(10)
Mg(1)--O(2) 2.0865(9) B(1)--H(11) 1.164(13) B(1)--H(12) 1.130(13)
B(1)--H(13) 1.091(15) B(2)--H(21) 1.187(13) B(2)--H(22) 1.137(13)
B(2)--H(23) 1.147(14) B(3)--H(31) 1.162(14) B(3)--H(32) 1.127(13)
B(3)--H(33) 1.112(14) B(4)--H(41) 1.154(12) B(4)--H(42) 1.177(14)
B(4)--H(43) 1.114(14) B(1)--N(1) 1.576(2) B(2)--N(1) 1.588(2)
B(3)--N(2) 1.581(2) B(4)--N(2) 1.5776(19) N(1)--C(1) 1.484(2)
N(1)--C(2) 1.4807(19) N(2)--C(3) 1.4847(19) N(2)--C(4) 1.483(2)
Bond Angles (deg) H(11)--Mg(1)--H(21) 78.0(5) H(11)--Mg(1)--H(31)
77.7(5) H(11)--Mg(1)--H(32) 75.0(5) H(11)--Mg(1)--H(41) 148.9(5)
H(11)--Mg(1)--H(42) 134.2(5) H(21)--Mg(1)--H(31) 117.6(5)
H(21)--Mg(1)--H(32) 70.2(5) H(21)--Mg(1)--H(41) 120.9(5)
H(21)--Mg(1)--H(42) 69.9(6) H(31)--Mg(1)--H(32) 48.2(5)
H(31)--Mg(1)--H(41) 71.6(5) H(31)--Mg(1)--H(42) 89.1(5)
H(32)--Mg(1)--H(41) 88.0(5) H(32)--Mg(1)--H(42) 64.1(5)
H(41)--Mg(1)--H(42) 51.4(5) B(1)--Mg(1)--B(2) 56.11(5)
B(1)--Mg(1)--B(3) 107.59(6) B(3)--Mg(1)--B(2) 111.14(6)
B(4)--Mg(1)--B(1) 161.98(6) B(4)--Mg(1)--B(2) 114.43(6)
B(4)--Mg(1)--B(3) 59.36(5) O(1)--Mg(1)--B(1) 88.65(5)
O(1)--Mg(1)--B(2) 136.33(5) O(1)--Mg(1)--B(3) 103.16(5)
O(1)--Mg(1)--B(4) 105.91(5) O(2)--Mg(1)--B(1) 103.57(5)
O(2)--Mg(1)--B(2) 86.22(5) O(2)--Mg(1)--B(3) 148.83(5)
O(2)--Mg(1)--B(4) 90.19(5) O(2)--Mg(1)--O(1) 77.38(4)
H(11)--B(1)--H(12) 108.7(9) H(11)--B(1)--H(13) 108.4(10)
H(12)--B(1)--H(13) 111.8(10) H(21)--B(2)--H(22) 109.0(9)
H(21)--B(2)--H(23) 108.9(9) H(22)--B(2)--H(23) 111.8(9)
H(31)--B(3)--H(32) 108.8(9) H(31)--B(3)--H(33) 107.9(9)
H(32)--B(3)--H(33) 113.5(9) H(41)--B(4)--H(42) 108.3(9)
H(41)--B(4)--H(43) 108.7(10) H(42)--B(4)--H(43) 110.0(10)
B(1)--N(1)--B(2) 109.61(11) B(4)--N(2)--B(3) 109.11(11)
N(1)--B(1)--Mg(1) 100.28(9) N(1)--B(2)--Mg(1) 90.02(8)
N(2)--B(3)--Mg(1) 94.10(8) N(2)--B(4)--Mg(1) 96.93(9)
C(1)--N(1)--B(1) 110.46(13) C(1)--N(1)--B(2) 108.26(12)
C(2)--N(1)--B(1) 109.50(12) C(2)--N(1)--B(2) 110.71(13)
C(3)--N(2)--B(3) 109.85(12) C(3)--N(2)--B(4) 109.90(12)
C(4)--N(2)--B(3) 110.11(12) C(4)--N(2)--B(4) 109.40(12)
C(2)--N(1)--C(1) 108.29(13) C(4)--N(2)--C(3) 108.46(13)
N(1)--B(2)--H(21) 108.4(6) N(1)--B(2)--H(22) 108.7(7)
N(1)--B(2)--H(23) 109.8(7) N(2)--B(3)--H(31) 107.0(7)
N(2)--B(3)--H(32) 107.3(7) N(2)--B(3)--H(33) 112.1(7)
N(2)--B(4)--H(41) 107.1(7) N(2)--B(4)--H(42) 108.5(7)
Example 13
TABLE-US-00008 [0582] TABLE 5 Bond Lengths (.ANG.) Mg(1)--H(11)
2.30(4) Mg(1)--H(12) 2.18(4) Mg(1)--H(21) 2.17(4) Mg(1)--H(22)
2.21(4) Mg(1)--B(1) 2.534(7) Mg(1)--B(2) 2.554(8) Mg(1)--C(1)
2.374(5) Mg(1)--C(2) 2.386(5) Mg(1)--C(3) 2.414(6) Mg(1)--C(4)
2.393(5) Mg(1)--C(5) 2.360(5) Mg(1)--O(1) 2.055(3) B(1)--H(11)
1.22(4) B(1)--H(12) 1.05(3) B(1)--H(13) 1.15(3) B(2)--H(21) 1.18(4)
B(2)--H(22) 1.05(4) B(2)--H(23) 1.07(4) N(1)--B(1) 1.570(7)
N(1)--B(2) 1.564(7) N(1)--C(11) 1.476(5) N(1)--C(12) 1.484(5) Bond
Angles (deg) H(11)--Mg(1)--H(12) 49.8(13) H(11)--Mg(1)--H(21)
69.6(14) H(11)--Mg(1)--H(22) 91.8(14) H(12)--Mg(1)--H(21) 90.1(15)
H(12)--Mg(1)--H(22) 72.4(13) H(21)--Mg(1)--H(22) 48.1(14)
B(1)--Mg(1)--B(2) 60.6(2) O(1)--Mg(1)--B(1) 103.9(2)
O(1)--Mg(1)--B(2) 101.0(2) H(11)--B(1)--H(12) .sup. 113(3)
H(11)--B(1)--H(13) .sup. 109(3) H(12)--B(1)--H(13) .sup. 106(3)
H(21)--B(2)--H(22) .sup. 106(3) H(21)--B(2)--H(23) .sup. 107(3)
H(22)--B(2)--H(23) .sup. 110(3) B(2)--N(1)--B(1) 110.1(4)
N(1)--B(1)--Mg(1) 94.9(4) N(1)--B(2)--Mg(1) 94.3(4)
C(11)--N(1)--B(1) 110.8(5) C(11)--N(1)--B(2) 110.0(5)
C(12)--N(1)--B(1) 109.0(4) C(12)--N(1)--B(2) 108.2(5)
C(11)--N(1)--C(12) 108.7(4) N(1)--B(1)--H(11) 109.8(19)
N(1)--B(1)--H(12) .sup. 109(2) N(1)--B(1)--H(13) 110.8(18)
N(1)--B(2)--H(21) .sup. 108(2) N(1)--B(2)--H(22) .sup. 111(2)
N(1)--B(2)--H(23) .sup. 114(2)
Example 14
TABLE-US-00009 [0583] TABLE 1 1 2 3 4 formula
C.sub.12H.sub.72B.sub.12N.sub.6Y.sub.2
C.sub.12H.sub.72B.sub.12N.sub.6Dy.sub.2
C.sub.10H.sub.44B.sub.6N.sub.3OY C.sub.10H.sub.44B.sub.6N.sub.3ODy
formula weight 608.30 755.48 376.25 .sup. 449.84 T, .degree. C. -80
-80 -80 -80 space group Pna2.sub.1 Pna2.sub.1 Pca2.sub.1 Pca2.sub.1
a, .ANG. 28.546(3) 28.4566(15) 21.868(7) 21.8439(11) b, .ANG.
14.0655(14) 14.0202(7) 10.395(4) 10.4025(5) c, .ANG. 9.4086(7)
9.3884(5) 20.630(7) 20.6450(11) V, .ANG..sup.3 3777.6(6) 3745.5(3)
4689(3) 4691.2(4) Z 4 4 8 8 .rho..sub.calcd, g cm.sup.-3 1.070
1.340 1.066 .sup. 1.274 .lamda., .ANG. 0.71073 0.71073 0.71073
0.71073 .mu..sub.calcd, cm.sup.-1 30.69 39.71 24.86 .sup. 31.84
transmissn coeff 0.685-0.838 N/A 0.400-0.512 0.503-0.798 unique
reflns 9025 9596 8605 10934 parameters 314 322 536 500
R.sub.1.sup.a 0.0462 0.0436 0.0539.sup. 0.0364 wR.sub.2.sup.b
0.0852 0.1022 0.0877.sup. 0.0724 .sup.aR.sub.1 = .SIGMA.| |F.sub.o|
- F.sub.c| |/.SIGMA.|F.sub.o| for reflections with F.sub.o.sup.2
> 2 .sigma.(F.sub.o.sup.2). .sup.bwR.sub.2 =
[.SIGMA.w(F.sub.o.sup.2 - F.sub.c.sup.2).sup.2/.SIGMA.
w(F.sub.o.sup.2).sup.2].sup.1/2 for all reflections.
Example 14
TABLE-US-00010 [0584] TABLE 2 Bond Lengths (.ANG.) Y(1)--B(1)
2.701(7) Y(1)--B(2) 2.739(7) Y(1)--B(3) 2.718(7) Y(1)--B(4)
2.756(7) Y(2)--B(5) 2.719(8) Y(2)--B(6) 2.763(7) Y(2)--B(7)
2.732(7) Y(2)--B(8) 2.717(7) Y(1)--B(11) 2.837(7) Y(2)--B(12)
2.672(7) Y(1)--B(21) 2.734(7) Y(2)--B(22) 2.853(7) B(1)--N(1)
1.562(8) B(2)--N(1) 1.565(9) B(3)--N(2) 1.554(8) B(4)--N(2)
1.558(8) B(5)--N(3) 1.561(8) B(6)--N(3) 1.580(8) B(7)--N(4)
1.578(9) B(8)--N(4) 1.563(8) B(11)--N(11) 1.545(8) B(12)--N(11)
1.609(7) B(21)--N(21) 1.576(7) B(22)--N(21) 1.551(8) N(1)--C(1)
1.492(7) N(1)--C(2) 1.481(8) N(2)--C(3) 1.490(7) N(2)--C(4)
1.458(7) N(3)--C(5) 1.477(7) N(3)--C(6) 1.476(8) N(4)--C(7)
1.469(7) N(4)--C(8) 1.508(7) N(11)--C(11) 1.478(7) N(11)--C(12)
1.515(7) N(21)--C(21) 1.496(7) N(21)--C(22) 1.463(7) Bond Angles
(deg) B(1)--Y(1)--B(2) 56.1(2) B(3)--Y(1)--B(4) 55.2(2)
B(11)--Y(1)--B(21) 90.7(2) B(5)--Y(2)--B(6) 55.7(2)
B(7)--Y(2)--B(8) 55.6(2) B(12)--Y(1)--B(22) 91.1(2)
B(1)--N(1)--B(2) 109.7(5) B(3)--N(2)--B(4) 109.2(5)
B(5)--N(3)--B(6) 109.3(5) B(7)--N(4)--B(8) 107.9(5)
B(11)--N(11)--B(12) 113.7(5) B(22)--N(21)--B(21) 112.1(5)
C(1)--N(1)--B(1) 109.1(5) C(1)--N(1)--B(2) 110.6(5)
C(2)--N(1)--B(1) 110.5(5) C(2)--N(1)--B(2) 107.4(5)
C(2)--N(1)--C(1) 109.5(6) C(3)--N(2)--B(3) 110.1(5)
C(3)--N(2)--B(4) 109.3(5) C(4)--N(2)--B(3) 111.0(5)
C(4)--N(2)--B(4) 109.0(5) C(4)--N(2)--C(3) 108.2(5)
C(5)--N(3)--B(5) 109.9(5) C(5)--N(3)--B(6) 109.0(5)
C(6)--N(3)--B(5) 110.9(5) C(6)--N(3)--B(6) 107.8(5)
C(6)--N(3)--C(5) 110.0(5) C(7)--N(4)--B(7) 111.9(5)
C(7)--N(4)--B(8) 109.7(5) C(7)--N(4)--C(8) 108.8(5)
C(8)--N(4)--B(7) 109.2(5) C(8)--N(4)--B(8) 109.3(5)
C(11)--N(11)--B(11) 108.3(5) C(11)--N(11)--B(12) 109.3(4)
C(11)--N(11)--C(12) 107.2(5) C(12)--N(11)--B(11) 108.6(5)
C(12)--N(11)--B(12) 109.5(4) C(21)--N(21)--B(21) 108.5(5)
C(21)--N(21)--B(22) 108.8(5) C(22)--N(21)--B(21) 109.7(5)
C(22)--N(21)--B(22) 109.2(5) C(22)--N(21)--C(21) 108.5(5)
Example 14
TABLE-US-00011 [0585] TABLE 3 Bond Lengths (.ANG.) Dy(1)--B(1) 2.73
Dy(1)--B(2) 2.73 Dy(1)--B(3) 2.76 Dy(1)--B(4) 2.70 Dy(2)--B(5) 2.72
Dy(2)--B(6) 2.75 Dy(2)--B(7) 2.74 Dy(2)--B(8) 2.72 Dy(1)--B(11)
2.68 Dy(2)--B(12) 2.84 Dy(1)--B(21) 2.84 Dy(2)--B(22) 2.73
B(1)--N(1) 1.547(19) B(2)--N(1) 1.587(17) B(3)--N(2) 1.580(14)
B(4)--N(2) 1.511(15) B(5)--N(3) 1.579(17) B(6)--N(3) 1.577(18)
B(7)--N(4) 1.568(14) B(8)--N(4) 1.542(16) B(11)--N(11) 1.588(16)
B(12)--N(11) 1.532(14) B(21)--N(21) 1.573(13) B(22)--N(21)
1.584(13) N(1)--C(1) 1.493(18) N(1)--C(2) 1.481(15) N(2)--C(3)
1.485(16) N(2)--C(4) 1.518(14) N(3)--C(5) 1.503(16) N(3)--C(6)
1.44(2) N(4)--C(7) 1.485(13) N(4)--C(8) 1.452(14) N(11)--C(11)
1.461(17) N(11)--C(12) 1.520(15) N(21)--C(21) 1.471(11)
N(21)--C(22) 1.446(13) Bond Angles (deg) B(1)--Dy(1)--B(2) 55.3
B(3)--Dy(1)--B(4) 55.6 B(11)--Dy(1)--B(21) 91.8 B(5)--Dy(2)--B(6)
55.8 B(7)--Dy(2)--B(8) 55.7 B(12)--Dy(1)--B(22) 90.2
B(1)--N(1)--B(2) 107.9(11) B(3)--N(2)--B(4) 110.8(9)
B(5)--N(3)--B(6) 108.4(9) B(7)--N(4)--B(8) 110.2(9)
B(11)--N(11)--B(12) 113.2(10) B(21)--N(21)--B(22) 109.4(8)
B(1)--N(1)--B(2) 107.9(11) C(1)--N(1)--B(1) 111.1(9)
C(1)--N(1)--B(2) 108.7(12) C(2)--N(1)--B(1) 110.4(12)
C(2)--N(1)--B(2) 107.3(10) C(2)--N(1)--C(1) 111.3(12)
C(3)--N(2)--B(3) 109.3(10) C(3)--N(2)--B(4) 112.1(10)
C(3)--N(2)--C(4) 106.3(10) C(4)--N(2)--B(3) 107.7(10)
C(4)--N(2)--B(4) 110.5(10) C(5)--N(3)--B(5) 106.8(12)
C(5)--N(3)--B(6) 108.3(11) C(6)--N(3)--B(5) 110.5(12)
C(6)--N(3)--B(6) 111.9(13) C(6)--N(3)--C(5) 110.9(11)
C(7)--N(4)--B(7) 110.8(9) C(7)--N(4)--B(8) 107.9(10)
C(8)--N(4)--B(7) 111.3(10) C(8)--N(4)--B(8) 111.2(9)
C(8)--N(4)--C(7) 105.4(9) C(11)--N(11)--B(11) 110.8(8)
C(11)--N(11)--B(12) 108.9(11) C(11)--N(11)--C(12) 108.5(11)
C(12)--N(11)--B(11) 107.7(10) C(12)--N(11)--B(12) 107.6(8)
C(21)--N(21)--B(21) 107.8(8) C(21)--N(21)--B(22) 110.6(7)
C(22)--N(21)--B(21) 108.6(9) C(22)--N(21)--B(22) 112.9(8)
Example 14
TABLE-US-00012 [0586] TABLE 4 Bond Lengths (.ANG.) Y(1)--H(11)
2.41(5) Y(1)--H(12) 2.23(4) Y(1)--H(21) 2.37(4) Y(1)--H(22) 2.44(4)
Y(1)--H(31) 2.37(4) Y(1)--H(32) 2.60(5) Y(1)--H(41) 2.41(4)
Y(1)--H(42) 2.30(4) Y(1)--H(51) 2.58(6) Y(1)--H(52) 2.27(5)
Y(1)--H(61) 2.29(5) Y(1)--H(62) 2.36(5) Y(1)--B(1) 2.807(8)
Y(1)--B(2) 2.836(8) Y(1)--B(3) 2.867(7) Y(1)--B(4) 2.773(7)
Y(1)--B(5) 2.891(9) Y(1)--B(6) 2.765(8) Y(1)--O(1) 2.441(4)
B(1)--H(11) 1.12(3) B(1)--H(12) 1.14(3) B(1)--H(13) 1.11(3)
B(2)--H(21) 1.11(3) B(2)--H(22) 1.14(3) B(2)--H(23) 1.08(3)
B(3)--H(31) 1.13(3) B(3)--H(32) 1.11(3) B(3)--H(33) 1.11(3)
B(4)--H(41) 1.12(3) B(4)--H(42) 1.10(3) B(4)--H(43) 1.10(3)
B(5)--H(51) 1.11(3) B(5)--H(52) 1.13(3) B(5)--H(53) 1.11(3)
B(6)--H(61) 1.12(3) B(6)--H(62) 1.07(3) B(6)--H(63) 1.08(3)
B(1)--N(1) 1.557(8) B(2)--N(1) 1.593(8) B(3)--N(2) 1.580(9)
B(4)--N(2) 1.541(9) B(5)--N(3) 1.559(9) B(6)--N(3) 1.572(9)
N(1)--C(1) 1.491(7) N(1)--C(2) 1.477(7) N(2)--C(3) 1.499(7)
N(2)--C(4) 1.472(7) N(3)--C(5) 1.476(7) N(3)--C(6) 1.473(7) Bond
Angles (deg) B(1)--Y(1)--B(2) 53.7(2) B(3)--Y(1)--B(4) 53.6(2)
B(5)--Y(1)--B(6) 53.0(2) B(1)--Y(1)--B(3) 139.9(2) B(1)--Y(1)--B(5)
104.5(3) B(2)--Y(1)--B(3) 88.8(2) B(2)--Y(1)--B(5) 91.9(2)
B(3)--Y(1)--B(5) 88.9(2) B(4)--Y(1)--B(1) 115.6(2) B(4)--Y(1)--B(2)
103.1(2) B(6)--Y(1)--B(1) 115.8(3) B(6)--Y(1)--B(2) 142.1(2)
B(6)--Y(1)--B(3) 102.6(3) B(6)--Y(1)--B(4) 112.8(2)
O(1)--Y(1)--B(1) 74.71(18) O(1)--Y(1)--B(2) 123.71(18)
O(1)--Y(1)--B(3) 127.86(18) O(1)--Y(1)--B(4) 78.08(19)
O(1)--Y(1)--B(5) 124.57(19) O(1)--Y(1)--B(6) 76.9(2)
C(2)--N(1)--C(1) 108.5(4) C(2)--N(1)--B(1) 111.7(5)
C(1)--N(1)--B(1) 108.9(5) C(2)--N(1)--B(2) 109.8(5)
C(1)--N(1)--B(2) 109.8(5) B(1)--N(1)--B(2) 108.2(5)
C(4)--N(2)--C(3) 108.3(5) C(4)--N(2)--B(4) 109.8(5)
C(3)--N(2)--B(4) 110.0(5) C(4)--N(2)--B(3) 110.3(5)
C(3)--N(2)--B(3) 109.3(5) B(4)--N(2)--B(3) 109.2(5)
C(6)--N(3)--C(5) 108.0(5) C(6)--N(3)--B(5) 110.3(5)
C(5)--N(3)--B(5) 111.7(5) C(6)--N(3)--B(6) 109.6(5)
C(5)--N(3)--B(6) 109.7(5) B(5)--N(3)--B(6) 107.6(5)
Example 14
TABLE-US-00013 [0587] TABLE 5 Bond Lengths (.ANG.) Dy(1)--B(1)
2.803(7) Dy(1)--B(2) 2.830(6) Dy(1)--B(3) 2.847(7) Dy(1)--B(4)
2.784(6) Dy(1)--B(5) 2.768(7) Dy(1)--B(6) 2.894(7) Dy(1)--O(1)
2.449(4) B(1)--N(1) 1.582(8) B(2)--N(1) 1.575(8) B(3)--N(2)
1.580(9) B(4)--N(2) 1.566(10) B(5)--N(3) 1.589(9) B(6)--N(3)
1.591(8) C(1)--N(1) 1.492(7) C(2)--N(1) 1.475(6) C(5)--N(3)
1.463(8) C(6)--N(3) 1.481(7) N(2)--C(3) 1.479(8) N(2)--C(4)
1.490(7) N(4)--B(7) 1.583(8) N(4)--B(8) 1.564(7) N(4)--C(7)
1.491(7) N(4)--C(8) 1.504(7) Bond Angles (deg) B(1)--Dy(1)--B(2)
53.6(2) B(3)--Dy(1)--B(4) 53.0(2) B(5)--Dy(1)--B(6) 53.7(2)
B(2)--N(1)--B(1) 107.2(4) C(1)--N(1)--B(1) 108.2(4)
C(1)--N(1)--B(2) 110.4(5) C(2)--N(1)--B(1) 111.6(4)
C(2)--N(1)--B(2) 110.5(5) C(2)--N(1)--C(1) 108.9(4)
B(4)--N(2)--B(3) 108.7(4) C(3)--N(2)--B(3) 109.4(5)
C(3)--N(2)--B(4) 109.1(5) C(3)--N(2)--C(4) 108.4(5)
C(4)--N(2)--B(3) 111.4(5) C(4)--N(2)--B(4) 109.8(5)
B(5)--N(3)--B(6) 107.2(5) C(5)--N(3)--B(5) 110.0(5)
C(5)--N(3)--B(6) 111.2(5) C(5)--N(3)--C(6) 108.6(5)
C(6)--N(3)--B(5) 108.6(5) C(6)--N(3)--B(6) 111.1(5)
Example 15
TABLE-US-00014 [0588] TABLE 1 Catalyst Film Composition
Ti(H.sub.3BNMe.sub.2BH.sub.3).sub.2 Mg.sub.0.8Ti.sub.0.2B.sub.2
Ti(BH.sub.4).sub.3(dme) Mg.sub.0.8Ti.sub.0.2B.sub.2
Zr(BH.sub.4).sub.4 Mg.sub.0.75Zri.sub.0.25B.sub.2
Hf(BH.sub.4).sub.4 Mg.sub.0.75Hfi.sub.0.25B.sub.2
Cr(H.sub.3BNMe.sub.2BH.sub.3).sub.2 Mg.sub.0.7Cr.sub.0.3B.sub.2
Y(DMDBA).sub.3(thf) Mg.sub.0.45Y.sub.0.55B.sub.3.5
Ti(NMe.sub.2).sub.4 Mg.sub.3Ti.sub.2B.sub.3C.sub.5N.sub.7
CpPd(allyl) MgPdBC.sub.2 TiNp.sub.4 no growth Ni(MeCp).sub.2 no
growth Cp*Mg(DMDBA)(thf) no growth EtI no growth I.sub.2 no growth
MeNHNH.sub.2 no growth
Example 16
TABLE-US-00015 [0589] TABLE 1 Precursor Precursors delivery
Co-reactant Ref. Mg diketonate >150.degree. C., with O.sub.2
[14, 38-47] (thd, hfac, dpm) carrier gas Mg(dpm).sub.2(TMEDA)
>100.degree. C., with O.sub.2 [48] carrier gas Mg(hfca).sub.2L
40.degree. C., with O.sub.2 [33] carrier gas MethylMg 140.degree.
C., with -- [16, 34] tert-Butoxide carrier gas Bis-cyclopentadienyl
40.degree. C., with H.sub.2O, O.sub.2 [21, 22, Mg carrier gas
49-52] Mg(DMDBA).sub.2 RT, no carrier H.sub.2O this work gas
needed
REFERENCES
[0590] (1) Pierson, J. F.; Bertran, F.; Bauer, J. P.; Jolly, J.
Surface & Coatings Technology 2001, 142, 906-910. [0591] (2)
Kelesoglu, E.; Mitterer, C.; Kazmanli, M. K.; Urgen, M. Surface and
Coatings Technology 1999, 116-119, 133-140. [0592] (3) Bazhin, A.
I.; Goncharov, A. A.; Petukhov, V. V.; Radjabov, T. D.; Stupak, V.
A.; Konovalov, V. A. Vacuum 2006, 80, 918-922. [0593] (4) Lin, S.
T.; Lee, C. Journal of the Electrochemical Society 2003, 150,
G607-G611. [0594] (5) Dahm, K. L.; Jordan, L. R.; Haase, J.;
Dearnley, P. A. Surface & Coatings Technology 1998, 109,
413-418. [0595] (6) Beckloff, B. N.; Lackey, W. J. Journal of the
American Ceramic Society 1999, 82, 503-512. [0596] (7) Motojima,
S.; Funahashi, K.; Kurosawa, K. Thin Solid Films 1990, 189, 73-79.
[0597] (8) Mukaida, M.; Goto, T.; Hirai, T. Journal of Materials
Science 1990, 25, 1069-1075. [0598] (9) Randich, E. Thin Solid
Films 1980, 72, 517-522. [0599] (10) Sung, J. W.; Goedde, D. M.;
Girolami, G. S.; Abelson, J. R. Journal of Applied Physics 2002,
91, 3904-3911. [0600] (11) Jayaraman, S.; Yang, Y.; Kim, D. Y.;
Girolami, G. S.; Abelson, J. R. Journal of Vacuum Science &
Technology A 2005, 23, 1619-1625. [0601] (12) Jayaraman, S.; Klein,
E. J.; Yang, Y.; Kim, D. Y.; Girolami, G. S.; Abelson, J. R.
Journal of Vacuum Science & Technology A 2005, 23, 631-633.
[0602] (13) Goedde, D. M.; Girolami, G. S. Journal of the American
Chemical Society 2004, 126, 12230-12231. [0603] (14) Liu, Z. K.;
Schlom, D. G.; Li, Q.; Xi, X. X. Applied Physics Letters 2001, 78,
3678-3680. [0604] (15) Kang, W. N.; Kim, H. J.; Choi, E. M.; Jung,
C. U.; Lee, S. L. Science 2001, 292, 1521-1523. [0605] (16) Ueda,
K.; Makimoto, T. Japanese Journal of Applied Physics Part 1-Regular
Papers Brief Communications & Review Papers 2006, 45,
5738-5741. [0606] (17) Ueda, K.; Naito, M. Journal of Applied
Physics 2003, 93, 2113-2120. [0607] (18) Zeng, X. H.; Pogrebnyakov,
A. V.; Kotcharov, A.; Jones, J. E.; Xi, X. X.; Lysczek, E. M.;
Redwing, J. M.; Xu, S. Y.; Lettieri, J.; Schlom, D. G.; Tian, W.;
Pan, X. Q.; Liu, Z. K. Nature Materials 2002, 1, 35-38. [0608] (19)
Zeng, X.; Pogrebnyakov, A.; Xi, X.; Redwing, J. M.; Lui, Z.-K.;
Schlom, D. G. In PCT Int. Appl.; (Penn State Research Foundation,
USA). Wo, 2003.
Example 17
Synthesis of Actinide Boranamide Complexes
[0609] Experimental Section.
[0610] All operations were carried out in vacuum or under argon
using standard Schlenk techniques. Diethyl ether, tetrahydrofuran,
pentane, and toluene were distilled under nitrogen from
sodium/benzophenone immediately before use. Anhydrous LnCl.sub.3
(Ln=La, Ce, Pr, Nd, Sm, Eu, Er) and ThCl.sub.4 (Cerac) was used as
received. The starting materials
Na(H.sub.3BNMe.sub.2BH.sub.3),.sup.1 UCl.sub.4,.sup.2 and
PMe.sub.3.sup.3 were prepared by literature routes.
[0611] Elemental analyses were carried out by the University of
Illinois Microanalytical Laboratory. The IR spectra were recorded
on a Nicolet Impact 410 infrared spectrometer as Nujol mulls
between KBr plates. The .sup.1H data were obtained on a Varian
Unity 400 instrument at 399.951 MHz or on a Varian Unity Inova 600
at 599.765 MHz. The .sup.11B NMR data were collected on a General
Electric GN300WB instrument at 96.289 MHz or on a Varian Unity
Inova 600 instrument at 192.425 MHz. Chemical shifts are reported
in .delta. units (positive shifts to high frequency) relative to
tetramethylsilane (.sup.1H) or BF.sub.3.Et.sub.2O (.sup.11B). Field
ionization (FI) mass spectra were recorded on a Micromass 70-VSE
mass spectrometer. Melting points and decomposition temperatures
were determined in closed capillaries under argon on a
Thomas-Hoover Unimelt apparatus.
[0612] Tetrakis(N,N-dimethyldiboranamido)thorium(IV),
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4.
[0613] To a suspension of ThCl.sub.4 (0.47 g, 1.3 mmol) in
tetrahydrofuran (15 mL) at -78.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.47 g, 5.0 mmol) in
tetrahydrofuran (15 mL). The reaction mixture was allowed to warm
to room temperature and stirred for 36 h. After several hours the
mixture consisted of a gray-white precipitate and a clear solution.
The solution was filtered and the clear filtrate was evaporated to
dryness under vacuum. The residue was extracted with toluene
(3.times.15 mL). The extract was filtered and evaporated to dryness
under vacuum to afford a white powder. Most of the white powder was
dissolved in diethyl ether (60 mL). The resulting solution was
filtered, concentrated to ca. 40 mL and cooled to -20.degree. C. to
yield 0.20 g of colorless, block-shaped crystals. Another 30 mL of
diethyl ether was added to the remaining toluene extract and this
fraction was combined with the mother liquor. The solution was
concentrated to ca. 30 mL and cooled to -20.degree. C. to yield an
additional 0.08 g of crystals. Yield: 0.28 g (42%). Mp: 152.degree.
C. Anal. Calcd for C.sub.8H.sub.48B.sub.8N.sub.4Th: C, 18.51; H,
9.32; N, 10.80. Found: C, 18.51; H, 9.42; N, 10.45. .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. 4.24 (br q, BH.sub.3, 24
H), 2.11 (s, fwhm=4 Hz, NMe.sub.2, 24 H). .sup.11 B NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. -2.77 (q, J.sub.BH=91 Hz,
BH.sub.3). MS (FI) [fragment ion, relative abundance]: m/z 391
[Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sup.+, 25], 405
[Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4)(BH.sub.3).sup.+,
85], 448 [Th(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 100], 462
[Th(H.sub.3BNMe.sub.2BH.sub.3).sub.3(BH.sub.3).sup.+, 75], 796
Th.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(BH.sub.4).sub.3, 25], 853
[Th.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.5(BH.sub.4).sub.2.sup.+,
40], 910
[Th.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6(BH.sub.4).sup.+, 30],
967 [Th.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.7.sup.+, 20]. IR
(cm.sup.-1): 2420 s, 2330 m, 2264 s, 2208 vs, 2069 sh, 1400 w, 1275
s, 1240 s, 1186 m, 1161 s, 1132 s, 1036 m, 1011 s, 926 m, 903 w,
827 w, 806 w, 455 m.
[0614] Crystallographic Studies.
[0615] Single crystals of Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4,
crystallized from diethyl ether, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 9601 reflections yielded the cell
dimensions.
[0616] The orthorhombic lattice and systematic absences for 0kl
(k+l.noteq.2n) and h0l (h.noteq.2n) were consistent with space
groups Pna2.sub.1 and Pnma; the centrosymmetric group Pnma was
shown to be the correct choice by successful refinement of the
proposed model. The measured intensities were reduced to structure
factor amplitudes and their esd's by correction for background,
scan speed, and Lorentz and polarization effects. No corrections
for crystal decay were necessary, but a face-indexed absorption
correction was applied, the minimum and maximum transmission
factors being 0.486 and 0.845. Systematically absent reflections
were deleted and symmetry equivalent reflections were averaged to
yield the set of unique data. The reflection 020 was found to be a
statistical outlier and was deleted; the remaining 2436 unique data
were used in the least squares refinement.
[0617] The structure was solved using direct methods (SHELXTL). The
correct position for the thorium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2), where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.117P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. The boranyl hydrogen atoms were located in the difference
maps, and their positions were refined with independent isotropic
displacement parameters. The chemically equivalent B-H and H . . .
H distances within the BH.sub.3 units were constrained to be equal
within an esd of 0.01 .ANG.. The remaining hydrogen atoms were
placed in idealized positions; the methyl groups were allowed to
rotate about the N-C axis to find the best least-squares positions.
The displacement parameters for boranyl hydrogens were set equal to
1.2 times U.sub.eq for the attached boron; those for methyl
hydrogens were set to 1.5 times U.sub.eq for the attached carbon.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (1.47 e.ANG..sup.-3) was located 1.04 .ANG. from
Th1. A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0618]
Bis(N,N-dimethyldiboranamido)bis(tetrahydroborato)thorium(IV),
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sub.2.
[0619] Method A.
[0620] Sublimation of Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4 (0.15 g,
0.33 mmol) at 100.degree. C. at 10.sup.-2 Torr afforded white
microcrystals. Yield: 0.11 g (82%). Note: A small amount of
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.3(BH.sub.4), an intermediate in
the thermal conversion of Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4 to
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sub.2, is
present.
[0621] Method B.
[0622] Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4 (12 mg, 0.023 mmol) in
C.sub.7D.sub.8 (1.9 mL) was heated at 80.degree. C. The reaction
was monitored by .sup.11B NMR spectroscopy. Quantitative conversion
to 2 was complete after 7 hours. Anal. Calcd for
C.sub.8H.sub.48B.sub.8N.sub.4Th: C, 11.86; H, 7.96; N, 6.91. Found:
C, 12.63; H, 7.86; N, 7.34. .sup.1H{.sup.11B} NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 1.85 (s, fwhm=2 Hz, NMe.sub.2, 12 H), 4.29
(s, fwhm=2 Hz, BH.sub.4, 8 H), 4.35 (s, fwhm=2 Hz, BH.sub.3, 12 H).
.sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. -2.34
(quintet, J.sub.BH=89 Hz, BH.sub.4, 2 B), 0.88 (q, J.sub.BH=92 Hz,
BH.sub.3, 4 B). IR (cm.sup.-1): 2522 m, 2497 sh, 2453 s, 2428 sh,
2328 m, 2258 m, 2204 vs, 2168 s, 1277 s, 1238 s, 1217 vs, 1196 s,
1184 s, 1163 s, 1126 m, 1101 w, 1014 vs, 928 m, 899 w, 847 w, 438
m.
[0623] Crystallographic Studies.
[0624] Single crystals of
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sub.2, grown by
sublimation, were mounted on glass fibers with Krytox oil (Dupont)
and immediately cooled to -80.degree. C. in a cold nitrogen gas
stream on the diffractometer. Standard peak search and indexing
procedures gave rough cell dimensions, and least squares refinement
using 5156 reflections yielded the cell dimensions.
[0625] The monoclinic lattice and systematic absences 0k0
(k.noteq.2n) and h0l (l.noteq.2n) were uniquely consistent with the
space group P2.sub.1/c, which was confirmed by the success of the
subsequent refinement. The measured intensities were reduced to
structure factor amplitudes and their esd's by correction for
background, scan speed, and Lorentz and polarization effects. No
corrections for crystal decay were necessary, but a face-indexed
absorption correction was applied, the minimum and maximum
transmission factors being 0.323 and 0.690. Systematically absent
reflections were deleted and symmetry equivalent reflections were
averaged to yield the set of unique data. All 4133 unique data were
used in the least squares refinement.
[0626] The structure was solved using direct methods (SHELXTL). The
correct position for the thorium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w=[.sigma..sup.-2(F.sub.O.sup.2)].sup.-1. The analytical
approximations to the scattering factors were used, and all
structure factors were corrected for both real and imaginary
components of anomalous dispersion. In the final cycle of least
squares, independent anisotropic displacement factors were refined
for the non-hydrogen atoms. Hydrogen atoms bonded to boron were
located in the difference maps, and their positions were refined
with independent isotropic displacement parameters. The chemically
equivalent B-H and Th-H distances within the BH.sub.3 units of the
diboranamide ligands and the BH.sub.4 units were constrained to be
equal within an esd of 0.01 .ANG.. The remaining hydrogen atoms
were placed in idealized positions; the methyl groups were allowed
to rotate about the N-C axis to find the best least-squares
positions. The displacement parameters for the boron bound
hydrogens were set equal to 1.2 times U.sub.eq for the attached
boron; those for methyl hydrogens were set to 1.5 times U.sub.eq
for the attached carbon. No correction for isotropic extinction was
necessary. Successful convergence was indicated by the maximum
shift/error of 0.000 for the last cycle. The largest peak in the
final Fourier difference map (1.93 e.ANG..sup.-3) was located 0.46
.ANG. from Th1. A final analysis of variance between observed and
calculated structure factors showed no apparent errors.
[0627] Tris(N,N-dimethyldiboranamido)uranium(III),
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3.
[0628] To a suspension of UCl.sub.4 in diethyl ether at -78.degree.
C. was added a solution of sodium N,N-dimethyldiboranamide in
diethyl ether. The reaction mixture was allowed to warm to room
temperature and stirred for 18 hours. Gas slowly evolved and the
bright green solution gradually turned dark brown. The solution was
filtered and the brown filtrate was evaporated to dryness under
vacuum. The residue was extracted with toluene (2.times.25 mL). The
dark red extract was filtered, concentrated to 20 mL, and cooled to
-20.degree. C. to yield red microcrystals. Yield: 0.14 g (26%). MP:
156.degree. C. (dec). Anal. Calcd for
C.sub.6H.sub.36B.sub.6N.sub.3U: C, 15.90; H, 8.01; N, 9.27. Found:
C, 15.69; H, 7.50; N, 9.06. .sup.1H NMR (C.sub.7D.sub.8, 20.degree.
C.): .delta. 3.76 (br s, fwhm=2210 Hz, NMe.sub.2, 36 H). .sup.11B
NMR (C.sub.7D.sub.8, 20.degree. C.): .delta. 163.36 (br s, fwhm=510
Hz, BH.sub.3). IR (cm.sup.-1): 2399 vs, 2331 m, 2270 s, 2202 vs,
2168 s, 2094 sh, 1402 w, 1327 sh, 1265 s, 1238 s, 1215 s, 1182 m,
1166 s, 1161 s, 1132 m, 1032 m, 928 m, 902 w, 810 w, 760 w, 451
m.
[0629] Crystallographic Studies, Structural Isomer A.
[0630] Single crystals of U(H.sub.3BNMe.sub.2BH.sub.3).sub.3,
crystallized from pentane, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 7463 reflections yielded the cell
dimensions.
[0631] The monoclinic lattice and systematic absences 0k0
(k.noteq.2n) and h0l (l.noteq.2n) were uniquely consistent with the
space group P2.sub.1/c, which was confirmed by the success of the
subsequent refinement. The measured intensities were reduced to
structure factor amplitudes and their esd's by correction for
background, scan speed, and Lorentz and polarization effects. No
corrections for crystal decay were necessary, but a face-indexed
absorption correction was applied, the minimum and maximum
transmission factors being 0.190 and 0.843. Systematically absent
reflections were deleted and symmetry equivalent reflections were
averaged to yield the set of unique data. All 4251 unique data were
used in the least squares refinement.
[0632] The structure was solved using direct methods (SHELXTL).
Correct position for the uranium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.0318P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. Hydrogen atoms were placed in idealized positions with C-H
and B-H distances fixed at 0.98 and 1.15 .ANG., respectively; the
methyl and boranyl groups were allowed to rotate about the C-N axis
and the B-N axis, respectively, to find the best least-squares
positions. The displacement parameters for methyl hydrogens were
set to 1.5 times U.sub.eq for the attached carbon atoms and the
boranyl hydrogens were set to 1.2 times U.sub.eq for the attached
boron atoms. No correction for isotropic extinction was necessary.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (2.90 e.ANG..sup.-3) was located 0.96 .ANG. from Ul.
A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0633] Crystallographic Studies, Structural Isomer B.
[0634] Single crystals of U(H.sub.3BNMe.sub.2BH.sub.3).sub.3,
crystallized from toluene, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 14808 reflections yielded the cell
dimensions.
[0635] The monoclinic lattice and systematic absences 0k0
(k.noteq.2n) and h0l(l.noteq.2n) were uniquely consistent with the
space group P2.sub.1/c, which was confirmed by the success of the
subsequent refinement. The measured intensities were reduced to
structure factor amplitudes and their esd's by correction for
background, scan speed, and Lorentz and polarization effects. No
corrections for crystal decay were necessary but a face-indexed
absorption correction was applied, the minimum and maximum
transmission factors being 0.456 and 0.754. Systematically absent
reflections were deleted and symmetry equivalent reflections were
averaged to yield the set of unique data. All 5035 unique data were
used in the least squares refinement.
[0636] The structure was solved using direct methods (SHELXTL).
Correct position for the uranium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.374P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. The boranyl hydrogen atoms were located in the difference
maps, and their positions were refined with independent isotropic
displacement parameters. The chemically equivalent B-H distances
within the BH.sub.3 units were constrained to be equal within an
esd of 0.01 .ANG.. The remaining hydrogen atoms were placed in
idealized positions; the methyl groups were allowed to rotate about
the N-C axis to find the best least-squares positions. No
correction for isotropic extinction was necessary. Successful
convergence was indicated by the maximum shift/error of 0.000 for
the last cycle. The largest peak in the final Fourier difference
map (4.18 e.ANG..sup.-3) was located 0.96 .ANG. from Ul. A final
analysis of variance between observed and calculated structure
factors showed no apparent errors.
[0637] Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)uranium(III),
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0638] To a suspension of UCl.sub.4 (0.46 g, 1.2 mmol) in
tetrahydrofuran (25 mL) at -78.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.45 g, 4.8 mmol) in
tetrahydrofuran (25 mL). The reaction mixture was allowed to warm
to room temperature and stirred for 68 h. Gas slowly evolved and
after several hours the mixture consisted of a white precipitate
and a green solution. The green solution was filtered and the
filtrate was evaporated to dryness under vacuum to afford a sticky,
dark brown solid. The residue was extracted with pentane
(2.times.20 mL). The filtered extract was concentrated to ca. 7 mL
and cooled to -20.degree. C. to yield 0.11 g of round, brown
crystals. The mother liquor was concentrated to 4 mL and cooled to
-20.degree. C. to yield an additional 0.03 g of brown crystals.
Yield: 0.14 g (22%). MP: 135.degree. C. Anal. Calcd for
C.sub.10H.sub.44B.sub.6N.sub.3OU: C, 22.86; H, 8.44; N, 7.99.
Found: C, 22.84; H, 8.25; N, 7.66. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. -5.56 (b, fwhm=125 Hz, OCH.sub.2, 4 H),
-1.89 (b, fwhm=38 Hz, OCH.sub.2CH.sub.2, 4 H), 3.36 (s, fwhm=4 Hz,
CH.sub.3, 18 H), 104.40 (br q, J.sub.BH=90 Hz, BH.sub.3, 18 H).
.sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 152.77 (br s,
fwhm=180 Hz, BH.sub.3). MS (FI) [fragment ion, relative abundance]:
m/z 453 [U(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 100]. IR
(cm.sup.-1): 2390 vs, 2335 m, 2278 s, 2210 vs, 2173 sh, 2064 sh,
1400 w, 1236 s, 1217 s, 1186 s, 1169 s, 1136 s, 930 m, 903 w, 856
m, 837 m, 812 w, 451 m.
[0639] Crystallographic Studies.
[0640] Single crystals of U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf),
crystallized from pentane, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 8026 reflections yielded the cell
dimensions.
[0641] The cubic lattice and systematic absences hkl
(h+k+l.noteq.2n) were consistent with space groups lm-3, l23,
l2.sub.13, lm-3m, l-43m, and l432; the non-centrosymmetric group
l23 was shown to be the correct choice by successful refinement of
the proposed model. The measured intensities were reduced to
structure factor amplitudes and their esd's by correction for
background, scan speed, and Lorentz and polarization effects. No
corrections for crystal decay were necessary, but a face-indexed
absorption correction was applied, the minimum and maximum
transmission factors being 0.162 and 0.306. The reflections 011 and
103 were found to be statistical outliers and were deleted; the
remaining 1799 unique data were used in the least squares
refinement.
[0642] The structure was solved using direct methods (SHELXTL).
Correct position for the uranium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.0201P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. The tetrahydrofuran molecule is disordered about a
three-fold axis and its C-O and C-C bond distances were fixed at
1.48.+-.0.01 and 1.52.+-.0.01 .ANG., respectively. Hydrogen atoms
on the diboranamide ligands were placed in idealized positions with
C-H=0.98 .ANG. and B-H=1.15 .ANG.; the methyl and boranyl groups
were allowed to rotate about their respective axis to find the best
least-squares positions. The displacement parameters for the
methylene and boranyl hydrogens were set equal to 1.2 times
U.sub.eq for the attached carbon and boron, respectively; those for
methyl hydrogens were set to 1.5 times U.sub.eq for the attached
carbon. No correction for isotropic extinction was necessary.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (0.58 e.ANG..sup.-3) was located 0.72 .ANG. from U1.
A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0643]
Tris(N,N-dimethyldiboranamido)bis(trimethylphosphine)uranium(III),
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(PMe.sub.3).sub.2.
[0644] To U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) (0.18 g, 0.34
mmol) in pentane (20 mL) was added trimethylphosphine (0.14 mL, 1.4
mmol). The brown solution immediately turned dark red. The solution
was stirred for 20 minutes, concentrated to 10 mL, and cooled to
-20.degree. C. to yield dark crystals. Yield: 0.13 g (64%). MP:
173.degree. C. (dec). Anal. Calcd for
C.sub.12H.sub.54B.sub.6N.sub.3P.sub.2U: C, 23.80; H, 8.99; N, 6.94.
Found: C, 23.73; H, 9.30; N, 6.80. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. -1.56 (br s, fwhm=110 Hz, PMe.sub.3, 18 H),
4.03 (s, fwhm=4 Hz, NMe.sub.2, 36 H), 98.32 (br s, fwhm=330 Hz,
BH.sub.3, 36 H). .sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.):
.delta. 152.45 (br s, fwhm=190 Hz, BH.sub.3). MS (FI) [fragment
ion, relative abundance]: m/z 454
[U(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 83], 530
[U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(PMe.sub.3).sup.+, 100], 601
[U(H.sub.3BNMe.sub.2BH.sub.3).sub.4(PMe.sub.3).sup.+, 75]. IR
(cm.sup.-1): 2357 vs, 2341 sh, 2276 m, 2214 vs, 2094 w, 1303 w,
1284 w, 1228 s, 1213 m, 1182 sh, 1163 vs, 1136 s, 947 m, 923 sh,
904 sh, 812 w, 459 m.
[0645] Crystallographic Studies.
[0646] Single crystals of
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(PMe.sub.3).sub.2, crystallized
from pentane, were mounted on glass fibers with Paratone-N oil
(Exxon) and immediately cooled to -80.degree. C. in a cold nitrogen
gas stream on the diffractometer. Standard peak search and indexing
procedures gave rough cell dimensions, and least squares refinement
using 9378 reflections yielded the cell dimensions.
[0647] The orthorhombic lattice and the systematic absences 0kl
(k.noteq.2n), h0l (l.noteq.2n), and hk0 (h.noteq.2n) were uniquely
consistent with the space group Pbca, which was confirmed by the
success of the subsequent refinement. The measured intensities were
reduced to structure factor amplitudes and their esd's by
correction for background, scan speed, and Lorentz and polarization
effects. No corrections for crystal decay were necessary, but a
face-indexed absorption correction was applied, the minimum and
maximum transmission factors being 0.272 and 0.799. Systematically
absent reflections were deleted and symmetry equivalent reflections
were averaged to yield the set of unique data. The reflections 104,
202, 002, 106, and 102 were statistical outliers and were deleted.
The remaining 6684 reflections were used in the least squares
refinement.
[0648] The structure was solved using direct methods (SHELXTL).
Correct position for the uranium atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.0238P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. Hydrogen atoms were placed in idealized positions with C-H
and B-H distances fixed at 0.98 and 1.15 .ANG., respectively; the
methyl and boranyl groups were allowed to rotate about the C-N axis
and the B-N axis, respectively, to find the best least-squares
positions. The displacement parameters for the boranyl hydrogens
were set equal to 1.2 times U.sub.eq for the attached boron; those
for methyl hydrogens were set to 1.5 times U.sub.eq for the
attached carbon. No correction for isotropic extinction was
necessary. Successful convergence was indicated by the maximum
shift/error of 0.000 for the last cycle. The largest peak in the
final Fourier difference map (0.75 e.ANG..sup.-3) was located 1.01
.ANG. from Ul. A final analysis of variance between observed and
calculated structure factors showed no apparent errors.
[0649]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)lanthanum(III),
La(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0650] Solid LaCl.sub.3 (0.52 g, 2.1 mmol) and solid
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.56 g, 5.9 mmol) were added to a
100 mL Schlenk tube with 30-40 steel balls (4.5 mm diameter). To
the solid mixture was added 2 mL tetrahydrofuran. The residue was
evaporated to dryness under vacuum and the flask was gently
agitated by hand for 30 min. Sublimation at 105.degree. C. at
10.sup.-2 Torr afforded white microcrystals. Yield: 33 mg (4%).
.sup.1H NMR (CH.sub.2Cl.sub.2, 20.degree. C.): .delta. 1.87 (m,
OCH.sub.2CH.sub.2, 4 H), 2.36 (s, fwhm=4 Hz, NMe.sub.2, 18 H), 3.85
(m, OCH.sub.2, 4 H). .sup.11B NMR (CH.sub.2Cl.sub.2, 20.degree.
C.): .delta. -4.27 (br q, J.sub.BH=90 Hz, BH.sub.3).
[0651] Crystallographic Studies.
[0652] Single crystals of La(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf),
grown by sublimation, were mounted on glass fibers with Paratone-N
oil (Exxon) and immediately cooled to -80.degree. C. in a cold
nitrogen gas stream on the diffractometer. Standard peak search and
indexing procedures gave rough cell dimensions, and least squares
refinement using 11511 reflections yielded the cell dimensions.
[0653] The cubic lattice and systematic absences hkl
(h+k+l.noteq.2n) were consistent with space groups lm-3, l23,
l2.sub.13, lm-3m, l-43m, l432, and l4.sub.132 the
non-centrosymmetric group l23 was shown to be the correct choice by
successful refinement of the proposed model. The measured
intensities were reduced to structure factor amplitudes and their
esd's by correction for background, scan speed, and Lorentz and
polarization effects. No corrections for crystal decay were
necessary, but a face-indexed absorption correction was applied,
the minimum and maximum transmission factors being 0.756 and 0.869.
The reflections 011 and 013 were found to be statistical outliers
and were deleted; the remaining 1514 unique data were used in the
least squares refinement.
[0654] The structure was solved using direct methods (SHELXTL).
Correct position for the lanthanum atom was deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma..sup.2(F.sub.O.sup.2)]}.sup.-1. The analytical
approximations to the scattering factors were used, and all
structure factors were corrected for both real and imaginary
components of anomalous dispersion. In the final cycle of least
squares, independent anisotropic displacement factors were refined
for the non-hydrogen atoms. The tetrahydrofuran molecule is
disordered about a three-fold axis and its C-O and C-C bond
distances were fixed at 1.48.+-.0.01 and 1.52.+-.0.01 .ANG.,
respectively. Hydrogen atoms on the diboranamide ligands were
placed in idealized positions with C-H=0.98 .ANG. and B-H=1.15
.ANG.; the methyl and boranyl groups were allowed to rotate about
their respective axis to find the best least-squares positions. The
displacement parameters for all hydrogen atoms were set to 1.5
times U.sub.eq for the attached carbon and 1.2 times for the
attached boron atom, except for those on the disordered
tetrahydrofuran molecule, which were not included in the model. An
isotropic extinction parameter was refined to a final value of
x=1.36(3).times.10.sup.-3 where F.sub.c is multiplied by the factor
k[1+F.sub.c.sup.2.times..lamda..sup.3/sin 2.theta.].sup.-1/4 with k
being the overall scale factor. Analysis of the diffraction
intensities suggested slight inversion twinning; therefore, the
intensities were calculated from the equation
l=xl.sub.a+(1-x)l.sub.b, where x is a scale factor that relates the
volumes of the inversion-related twin components. The scale factor
refined to a value of 0.67(7). Successful convergence was indicated
by the maximum shift/error of 0.000 for the last cycle. The largest
peak in the final Fourier difference map (1.17 e.ANG..sup.-3) was
located 1.12 .ANG. from H2A. A final analysis of variance between
observed and calculated structure factors showed no apparent
errors.
[0655] Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)cerium(III),
Ce(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0656] To a suspension of CeCl.sub.3 (0.27 g, 1.1 mmol) in
tetrahydrofuran (15 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.30 g, 3.2 mmol) in
tetrahydrofuran (12 mL). The white reaction mixture was stirred at
0.degree. C. for 10 minutes before being allowed to warm to room
temperature. The resulting white mixture was stirred for 15 h and
then evaporated to dryness under vacuum to afford a sticky, white
solid. The residue was extracted with pentane (2.times.25 mL). The
filtered extract was concentrated to ca. 5 mL and cooled to
-20.degree. C. to yield large, white crystals. Yield: 41 mg (9%).
MP: 132.degree. C. Anal. Calcd for
C.sub.10H.sub.44B.sub.6N.sub.30Ce: C, 28.10; H, 10.38; N, 9.83.
Found: C, 28.41; H, 11.23; N, 10.28. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 0.79 (s, fwhm=6 Hz, NMe.sub.2, 18 H), 3.84
(s, fwhm=12 Hz, OCH.sub.2CH.sub.2, 4 H), 7.11 (s, fwhm=22 Hz,
OCH.sub.2, 4 H), 20.39 (br q, J.sub.BH=92 Hz, BH.sub.3, 18 H).
.sup.11 B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 23.14 (br s,
fwhm=49 Hz, BH.sub.3). IR (cm.sup.-1): 2390 s, 2340 w, 2285 m, 2255
sh, 2216 vs, 2168 sh, 2064 w, 1235 s, 1216 s, 1186 s, 1169 vs, 1138
s, 929 w, 901 w, 855 m, 836 w, 809 w, 449 m.
[0657]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)praseodymium(III),
Pr(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0658] To a suspension of PrCl.sub.3 (0.26 g, 1.0 mmol) in
tetrahydrofuran (10 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.30 g, 3.2 mmol) in
tetrahydrofuran (10 mL). The pale green reaction mixture was
stirred at 0.degree. C. for 15 minutes before being allowed to warm
to room temperature. The resulting white mixture was stirred for 17
h and then evaporated to dryness under vacuum to afford a sticky
solid. The residue was extracted with pentane (2.times.10 mL). The
filtered pale green extract was concentrated to ca. 10 mL and
cooled to -20.degree. C. to yield large, pale green crystals.
Yield: 0.14 g (31%). MP: 134.degree. C. Anal. Calcd for
C.sub.10H.sub.44B.sub.6N.sub.30Pr: C, 28.05; H, 10.36; N, 9.81.
Found: C, 27.46; H, 10.76; N, 9.50. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 0.02 (s, fwhm=7 Hz, NMe.sub.2, 18 H), 6.48
(s, fwhm=13 Hz, OCH.sub.2CH.sub.2, 4 H), 9.93 (s, fwhm=22 Hz,
OCH.sub.2, 4 H), 58.06 (br d, J.sub.BH=98 Hz, BH.sub.3, 18 H).
.sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 75.13 (br s,
fwhm=200 Hz, BH.sub.3). IR (cm.sup.-1): 2390 vs, 2340 m, 2284 s,
2250 sh, 2213 vs, 2169 sh, 2066 w, 1262 s, 1237 s, 1216 s, 1185 m,
1170 s, 1137 s, 929 m, 901 w, 856 m, 812 w.
[0659]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)neodymium(III),
Nd(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0660] To a suspension of NdCl.sub.3 (0.26 g, 1.0 mmol) in
tetrahydrofuran (10 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.30 g, 3.2 mmol) in
tetrahydrofuran (10 mL). The pale green reaction mixture was
stirred at 0.degree. C. for 10 minutes before being allowed to warm
to room temperature. The resulting white mixture was stirred for 13
h and then evaporated to dryness under vacuum to afford a sticky
solid. The residue was extracted with pentane (12 mL). The filtered
lavender extract was concentrated to ca. 8 mL and cooled to
-20.degree. C. to yield 0.17 g of large, lavender crystals. The
mother liquor was concentrated to 4 mL and cooled to -20.degree. C.
to yield an additional 0.03 g of lavender crystals. Yield: 0.20 g
(45%). MP: 133.degree. C. Anal. Calcd for
C.sub.10H.sub.44B.sub.6N.sub.3ONd: C, 27.83; H, 10.28; N, 9.74.
Found: C, 27.80; H, 10.86; N, 10.00. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. 0.66 (s, fwhm=21 Hz, OCH.sub.2, 4 H), 0.95
(s, fwhm=9 Hz, OCH.sub.2CH.sub.2, 4 H), 3.06 (s, fwhm=7 Hz,
NMe.sub.2, 18 H), 82.86 (br s, fwhm=330 Hz, BH.sub.3, 18 H).
.sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 104.77 (br s,
fwhm=170 Hz, BH.sub.3). MS (FI) [fragment ion, relative abundance]:
m/z 358 [Nd(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 100], 645
[Nd.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.5.sup.+, 60], 1003
[Nd.sub.3(H.sub.3BNMe.sub.2BH.sub.3).sub.8.sup.+, 10]. IR
(cm.sup.-1): 2392 s, 2342 m, 2285 s, 2252 sh, 2216 vs, 2173 sh,
2066 w, 1264 s, 1238 s, 1216 s, 1186 s, 1170 s, 1137 s, 926 m, 902
w, 857 m, 813 w.
[0661]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)samarium(III),
Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0662] To a suspension of 5 mCl.sub.3 (0.30 g, 1.2 mmol) in
tetrahydrofuran (18 mL) at -78.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.33 g, 3.5 mmol) in
tetrahydrofuran (10 mL). The pale green reaction mixture was
stirred at -78.degree. C. for 25 minutes before being allowed to
warm to room temperature. The white suspension slowly turned to a
hazy yellow solution after several hours at room temperature. The
mixture was stirred for 14 h at room temperature and then
evaporated to dryness under vacuum to afford a sticky, ivory solid.
The residue was extracted with pentane (2.times.15 mL). The
filtered extract was concentrated to ca. 15 mL and cooled to
-20.degree. C. to yield 0.18 g of large, pale yellow crystals. The
mother liquor was concentrated to 7 mL and cooled to -20.degree. C.
to yield an additional 0.11 g of pale yellow crystals. Yield: 0.29
g (57%). MP: 134.degree. C. Anal. Calcd for
C.sub.10H.sub.44B.sub.6N.sub.3OSm: C, 27.44; H, 10.13; N, 9.60.
Found: C, 27.62; H, 11.02; N, 9.46. .sup.1H NMR (C.sub.6D.sub.6,
20.degree. C.): .delta. -1.86 (br q, J.sub.BH=104 Hz, BH.sub.3, 18
H), 1.29 (s, fwhm=10 Hz, OCH.sub.2CH.sub.2, 4 H), 3.80 (s, fwhm=14
Hz, OCH.sub.2, 4 H), 2.25 (s, fwhm=4 Hz, NMe.sub.2, 18 H). .sup.11B
NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. -9.79 (br q,
J.sub.BH=87 Hz, BH.sub.3). MS (FI) [fragment ion, relative
abundance]: m/z 362 [Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+,
100], 660 [Sm.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.5.sup.+, 80]. IR
(cm.sup.-1): 2496 sh, 2392 vs, 2344 m, 2286 s, 2255 m, 2218 vs,
2173 s, 2067 w, 1268 s, 1238 s, 1216 s, 1187 m, 1170 s, 1137 s,
1019 s, 924 m, 902 w, 856 m, 814 w, 457 m.
[0663] Crystallographic Studies.
[0664] Single crystals of Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf),
crystallized from pentane, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 33620 reflections yielded the cell
dimensions.
[0665] The orthorhombic lattice and systematic absences 0kl
(l.noteq.2n) and h0l (h.noteq.2n) were consistent with the space
groups Pca2.sub.1 and Pbcm; the non-centrosymmetric space group
Pca2.sub.1 was shown to be the correct choice by successful
refinement of the proposed model. The measured intensities were
reduced to structure factor amplitudes and their esd's by
correction for background, scan speed, and Lorentz and polarization
effects. No corrections for crystal decay were necessary but a
face-indexed absorption correction was applied, the minimum and
maximum transmission factors being 0.530 and 0.633. Systematically
absent reflections were deleted and symmetry equivalent reflections
were averaged to yield the set of unique data. All 15617 unique
data were used in the least squares refinement.
[0666] The structure was solved using direct methods (SHELXTL).
Correct positions for the samarium atoms were deduced from an
E-map. Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.0208P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. The C-O and C-C bond distances of the tetrahydrofuran
molecule were fixed at 1.48.+-.0.001 and 1.52.+-.0.001 .ANG.,
respectively. Hydrogen atoms were placed in idealized positions
with C-H=0.98 .ANG. and B-H=1.15 .ANG.; the methyl and boranyl
groups were allowed to rotate about their respective axis to find
the best least-squares positions. The displacement parameters for
the methylene and boranyl hydrogens were set equal to 1.2 times
U.sub.eq for the attached carbon and boron, respectively; those for
methyl hydrogens were set to 1.5 times U.sub.eq for the attached
carbon. No correction for isotropic extinction was necessary.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (0.84 e.ANG..sup.-3) was located 0.86 .ANG. from
Sm2. A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0667]
Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)europium(III),
Eu(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0668] To a suspension of EuCl.sub.3 (0.26 g, 1.0 mmol) in
tetrahydrofuran (15 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.29 g, 3.1 mmol) in
tetrahydrofuran (15 mL). The grey reaction mixture was stirred at
0.degree. C. for 25 minutes before being allowed to warm to room
temperature. The grey suspension slowly gained a yellow solution
after several hours at room temperature. The mixture was stirred
for 43 h at room temperature and then evaporated to dryness under
vacuum to afford a sticky, yellow solid. The residue was extracted
with pentane (3.times.5 mL). The yellow extract was filtered,
concentrated to ca. 5 mL, and cooled to -20.degree. C. to yield
large, bright yellow crystals. Yield: 0.24 g (55%). .sup.11B NMR
(C.sub.6F.sub.6, 20.degree. C.): .delta. -176.8 (br s,
J.sub.BH=2140 Hz, BH.sub.3).
[0669] Crystallographic Studies.
[0670] Single crystals of Eu(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf),
crystallized from pentane, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 14459 reflections yielded the cell
dimensions.
[0671] The orthorhombic lattice and systematic absences 0kl
(l.noteq.2n) and h0l (h.noteq.2n) were consistent with the space
groups Pca2.sub.1 and Pbcm; the non-centrosymmetric space group
Pca2.sub.1 was shown to be the correct choice by successful
refinement of the proposed model. The measured intensities were
reduced to structure factor amplitudes and their esd's by
correction for background, scan speed, and Lorentz and polarization
effects. No corrections for crystal decay were necessary but a
face-indexed absorption correction was applied, the minimum and
maximum transmission factors being 0.485 and 0.705. Systematically
absent reflections were deleted and symmetry equivalent reflections
were averaged to yield the set of unique data. The reflections 014,
413, and 403 were found to be statistical outliers and were
deleted; the remaining 8672 unique data were used in the least
squares refinement.
[0672] The structure was solved using direct methods (SHELXTL).
Correct positions for the europium atoms were deduced from an
E-map. Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The C28 atom in the tetrahydrofuran ring of molecule 2 was
disordered; to produce satisfactory ellipsoids, the atom was
partitioned over two positions and the site occupancy factors of
these positions were refined independently so that the sum of these
SOF's was equal to one. The quantity minimized by the least-squares
program was .SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O.sup.2)].sup.2+(0.0137P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. Hydrogen atoms were placed in idealized positions with
C-H=0.98 .ANG. and B-H=1.15 .ANG.; the methyl and boranyl groups
were allowed to rotate about their respective axis to find the best
least-squares positions. The displacement parameters for the
methylene and boranyl hydrogens were set equal to 1.2 times
U.sub.eq for the attached carbon and boron, respectively; those for
methyl hydrogens were set to 1.5 times U.sub.eq for the attached
carbon. No correction for isotropic extinction was necessary.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (0.68 e.ANG..sup.-3) was located 1.02 .ANG. from
Eu2. A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0673] Tris(N,N-dimethyldiboranamido)(tetrahydrofuran)erbium(III),
Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).
[0674] To a suspension of ErCl.sub.3 (2.11 g, 7.71 mmol) in
tetrahydrofuran (125 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (2.27 g, 24.0 mmol) in
tetrahydrofuran (50 mL). The pale pink reaction mixture was stirred
at 0.degree. C. for 15 minutes before being allowed to warm to room
temperature. The pink suspension slowly turned to a hazy pink
solution after several hours at room temperature. The mixture was
stirred for 42 h at room temperature and then evaporated to dryness
under vacuum to afford a sticky, pink solid. The residue was
extracted with pentane (3.times.40 mL). The filtered extract was
concentrated to ca. 50 mL and cooled to -20.degree. C. to yield
1.89 g of large, pale pink crystals. The mother liquor was
concentrated to 8 mL and cooled to -20.degree. C. to yield an
additional 0.61 g of pale pink crystals. Yield: 2.50 g (71%). MP:
114.degree. C. Anal. Calcd for C.sub.10H.sub.44B.sub.6N.sub.3OU: C,
26.42; H, 9.76; N, 9.24. Found: C, 26.43; H, 9.96; N, 9.17. .sup.1H
NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. -43.14 (br s, fwhm=250
Hz, OCH.sub.2, 4 H), -28.57 (s, fwhm=87 Hz, OCH.sub.2CH.sub.2, 4
H), 14.79 (s, fwhm=110 Hz, NMe.sub.2, 18 H), 108.45 (br s,
fwhm=2380 Hz, BH.sub.3). .sup.11B NMR (C.sub.6D.sub.6, 20.degree.
C.): .delta. -171.46 (s, fwhm=180 Hz, BH.sub.3). MS (FI) [fragment
ion, relative abundance]: m/z 381
[Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 100]. IR (cm.sup.-1):
2405 s, 2355 sh, 2297 m, 2293 m, 2230 vs, 2185 s, 2087 sh, 1286 s,
1242 s, 1219 m, 1173 vs, 1140 s, 926 w, 856 m, 849 w, 825 sh, 468
m.
[0675] Crystallographic Studies.
[0676] Single crystals of Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf),
crystallized from pentane, were mounted on glass fibers with
Paratone-N oil (Exxon) and immediately cooled to -80.degree. C. in
a cold nitrogen gas stream on the diffractometer. Standard peak
search and indexing procedures gave rough cell dimensions, and
least squares refinement using 14237 reflections yielded the cell
dimensions.
[0677] The orthorhombic lattice and systematic absences 0kl
(l.noteq.2n) and h0l (h.noteq.2n) were consistent with the space
groups Pca2.sub.1, and Pbcm; the non-centrosymmetric space group
Pca2.sub.1 was shown to be the correct choice by successful
refinement of the proposed model. The measured intensities were
reduced to structure factor amplitudes and their esd's by
correction for background, scan speed, and Lorentz and polarization
effects. No corrections for crystal decay were necessary but a
face-indexed absorption correction was applied, the minimum and
maximum transmission factors being 0.251 and 0.480. Systematically
absent reflections were deleted and symmetry equivalent reflections
were averaged to yield the set of unique data. The reflections 010,
110, and 11-2 were found to be statistical outliers and were
deleted; the remaining 8542 unique data were used in the least
squares refinement.
[0678] The structure was solved using direct methods (SHELXTL).
Correct positions for the erbium atoms were deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The C29 atom in the tetrahydrofuran ring of molecule 2 was
disordered; to produce satisfactory ellipsoids, the atom was
partitioned over two positions and the site occupancy factors of
these positions were refined independently so that the sum of these
SOF's was equal to one. The quantity minimized by the least-squares
program was .SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma..sup.2(F.sub.O.sup.2)]+(0.0181P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. Hydrogen atoms were placed in idealized positions with
C-H=0.98 .ANG. and B-H=1.15 .ANG.; the methyl and boranyl groups
were allowed to rotate about their respective axis to find the best
least-squares positions. The displacement parameters for the
methylene and boranyl hydrogens were set equal to 1.2 times
U.sub.eq for the attached carbon and boron, respectively; those for
methyl hydrogens were set to 1.5 times U.sub.eq for the attached
carbon. No correction for isotropic extinction was necessary.
Successful convergence was indicated by the maximum shift/error of
0.000 for the last cycle. The largest peak in the final Fourier
difference map (0.87 e.ANG..sup.-3) was located 0.83 .ANG. from
Er2. A final analysis of variance between observed and calculated
structure factors showed no apparent errors.
[0679] Hexakis(N,N-dimethyldiboranamido)dilanthanum(III),
La.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0680] Solid LaCl.sub.3 (0.51 g, 2.1 mmol) and solid
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.58 g, 6.1 mmol) were added to a
100 mL Schlenk tube with 30-40 steel balls (4.5 mm diameter). The
flask was gently agitated by hand for 20 min and the powdery solid
slowly became sticky. Sublimation at 125.degree. C. at 10.sup.-2
Torr afforded white microcrystals. Yield: 0.11 g (15%). Anal. Calcd
for C.sub.12H.sub.72B.sub.12N.sub.6La.sub.2: C, 20.35; H, 10.25; N,
11.87. Found: C, 20.56; H, 11.19; N, 11.93. .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. 2.22 (s, fwhm=40 Hz,
NMe.sub.2, 36), 2.78 (br q, J.sub.BH=110 Hz, BH.sub.3, 36).
.sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. -2.82 (br q,
J.sub.BH=79 Hz, BH.sub.3).
[0681] Hexakis(N,N-dimethyldiboranamido)dicerium(III),
Ce.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0682] Solid CeCl.sub.3 (0.53 g, 2.2 mmol) and solid
Na(H.sub.3BNMe.sub.2BH.sub.3) (0.66 g, 7.0 mmol) were added to a
250 mL round bottom flask with 30-40 steel balls (4.5 mm diameter).
The flask was gently agitated by hand for 30 min and the powdery
solid slowly became sticky. Sublimation at 110.degree. C. at
10.sup.-2 Torr afforded white microcrystals. Yield: 0.25 g (33%).
MP: 183.degree. C. (dec). Anal. Calcd for
C.sub.12H.sub.72B.sub.12N.sub.6Ce.sub.2: C, 20.28; H, 10.21; N,
11.82. Found: C, 20.60; H, 11.06; N, 11.67. .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. 4.23 (s, fwhm=40 Hz,
NMe.sub.2, 36), 26.39 (br s, fwhm=330 Hz, BH.sub.3, 36). .sup.11B
NMR (C.sub.6D.sub.6, 20.degree. C.): .delta. 39.83 (s, fwhm=190 Hz,
BH.sub.3). MS (FI) [fragment ion, relative abundance]: m/z 356
[Ce(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+, 100], 639
[Ce.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.sup.+, 35], 995
[Ce.sub.3(H.sub.3BNMe.sub.2BH.sub.3).sub.8.sup.+, 5].
[0683] Hexakis(N,N-dimethyldiboranamido)dierbium(III),
Er.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.
[0684] Sublimation of Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf)
(0.15 g, 0.33 mmol) at 75.degree. C. at 10.sup.-2 Torr afforded
pink microcrystals. Yield: 92 mg (73%). Anal. Calcd for
C.sub.12H.sub.72B.sub.12N.sub.6Er.sub.2: C, 18.84; H, 9.49; N,
10.99. Found: C, 19.55; H, 9.61; N, 10.97. .sup.1H NMR
(C.sub.6D.sub.6, 20.degree. C.): .delta. -32.50 (s, fwhm=150 Hz,
NMe.sub.2). .sup.11B NMR (C.sub.6D.sub.6, 20.degree. C.): .delta.
-324.43 (s, fwhm=240 Hz, BH.sub.3). MS (FI) [fragment ion, relative
abundance]: m/z 381 [Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3.sup.+,
100], 693 [Er.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.6.sup.+,
15].
[0685]
Tetrakis(N,N-dimethyldiboranamido)tetrakis(tetrahydrofuran)dieuropi-
um(II), Eu.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(thf).sub.4.
[0686] To a suspension of EuCl.sub.3 (0.50 g, 1.9 mmol) in
tetrahydrofuran (20 mL) at 0.degree. C. was added a solution of
sodium N,N-dimethyldiboranamide (0.56 g, 5.9 mmol) in
tetrahydrofuran (20 mL). The grey reaction mixture was stirred at
0.degree. C. for 15 minutes before being allowed to warm to room
temperature. The grey suspension slowly gained a yellow hue after
several hours at room temperature. The mixture was stirred for 40 h
at room temperature and then evaporated to dryness under vacuum to
afford a sticky, yellow solid. The residue was extracted with
pentane (2.times.20 mL). The pale yellow extract was filtered,
concentrated to ca. 15 mL, and cooled to -20.degree. C. to yield
pale yellow crystals. Yield: 0.39 g (47%).
[0687] Crystallographic Studies.
[0688] Single crystals of
Eu.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(thf).sub.4, crystallized
from pentane, were mounted on glass fibers with Paratone-N oil
(Exxon) and immediately cooled to -80.degree. C. in a cold nitrogen
gas stream on the diffractometer. Standard peak search and indexing
procedures gave rough cell dimensions, and least squares refinement
using 7317 reflections yielded the cell dimensions.
[0689] The monoclinic lattice and systematic absences 0k0
(k.noteq.2n) and h0l (l.noteq.2n) were uniquely consistent with the
space group P2.sub.1/c, which was confirmed by the success of the
subsequent refinement. The measured intensities were reduced to
structure factor amplitudes and their esd's by correction for
background, scan speed, and Lorentz and polarization effects. No
corrections for crystal decay were necessary, but a face-indexed
absorption correction was applied, the minimum and maximum
transmission factors being 0.594 and 0.734. Systematically absent
reflections were deleted and symmetry equivalent reflections were
averaged to yield the set of unique data. All 4865 unique data were
used in the least squares refinement.
[0690] The structure was solved using direct methods (SHELXTL).
Correct positions for europium atoms were deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
calculations revealed the positions of the remaining non-hydrogen
atoms. The europium centers and the bridging diboranamide ligands
are disordered over two positions related by a pseudo two-fold axis
running along the length of the molecule and passing approximately
through the nitrogen atoms of the two terminal diboranamide
ligands. The terminal diboranamides and the tetrahydrofuran
molecules of the two disordered components are essentially
superimposed and could be refined as full occupancy groups. The
site occupancy factors for these two disordered components were
constrained to sum one; the S.O.F. for the major occupancy
component refined to 0.690. The tetrahydrofuran molecules show
further disorder; one is disordered over two positions at the
.alpha.-carbons while the other is disordered over a two-fold
rotation. The site occupancy factors for the disordered components
were also constrained to the sum of one; the S.O.F. for the major
occupancy components refined to 0.512 and 0.563, respectively. The
quantity minimized by the least-squares program was
.SIGMA.w(F.sub.O.sup.2-F.sub.C.sup.2).sup.2, where
w={[.sigma.(F.sub.O)].sup.2+(0.421P).sup.2}.sup.-1 and
P=(F.sub.O.sup.2+2F.sub.C.sup.2)/3. The analytical approximations
to the scattering factors were used, and all structure factors were
corrected for both real and imaginary components of anomalous
dispersion. In the final cycle of least squares, independent
anisotropic displacement factors were refined for the non-hydrogen
atoms. The chemically equivalent C-N, B-N, B . . . C, and C . . . C
distances within the diboranamide ligands were constrained to be
equal within an esd of 0.005 .ANG.. The C-O and C-C distances in
the tetrahydrofuran molecules were constrained to be 1.48.+-.0.005
and 1.52.+-.0.005 .ANG., respectively. Hydrogen atoms were placed
in idealized positions; the methyl groups were allowed to rotate
about the C-C axis to find the best least-squares positions. The
displacement parameters for methylene and boranyl hydrogens were
set equal to 1.2 times U.sub.eq for the attached carbon and boron;
those for methyl hydrogens were set to 1.5 times U.sub.eq for the
attached carbon. No correction for isotropic extinction was
necessary. Successful convergence was indicated by the maximum
shift/error of 0.000 for the last cycle. The largest peak in the
final Fourier difference map (0.65 e.ANG..sup.-3) was located 0.95
.ANG. from Eu1. A final analysis of variance between observed and
calculated structure factors showed no apparent errors.
REFERENCES
[0691] 1. Noth, H.; Thomas, S., Metal tetrahydridoborates and
tetrahydroboratometalates. Part 24. Solvates of sodium
bis(borane)dimethylamide. Eur. J. Inorg. Chem. 1999, (8),
1373-1379. [0692] 2. Hermann, J. A.; Suttle, J. F., Inorg. Synth.
1978, 5, 143-145. [0693] 3. Leutkens, M. L.; Sattelberger, A. P.;
Murray, H. H.; Basil, J. D.; Fackler, J. P., Inorg. Synth. 1989,
26, 7-12.
TABLE-US-00016 [0693] TABLE 1 Selected Bond Lengths and Angles for
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.4.sup.a Bond Lengths (.ANG.)
Th(1)--B(1) 2.978(8) Th(1)--B(2) 2.881(8) Th(1)--B(3) 2.950(11)
Th(1)--B(4) 2.866(10) Th(1)--B(5) 2.860(12) Th(1)--B(6) 3.193(14)
B(1)--N(1) 1.566(9) B(2)--N(1) 1.570(9) B(3)--N(2) 1.588(12)
B(4)--N(2) 1.544(12) B(5)--N(3) 1.547(11) B(6)--N(3) 1.591(12)
N(1)--C(1) 1.486(8) N(1)--C(2) 1.481(7) N(2)--C(3) 1.484(7)
N(2)--C(4) 1.469(8) Bond Angles (deg) B(1)--Th(1)--B(2) 51.2(2)
B(3)--Th(1)--B(4) 51.7(3) B(5)--Th(1)--B(6) 49.6(3)
B(1)--N(1)--B(2) 107.6(5) B(3)--N(2)--B(4) 107.7(7)
B(5)--N(3)--B(6) 109.0(8) C(1)--N(1)--B(1) 110.1(6)
C(1)--N(1)--B(2) 110.0(6) C(2)--N(1)--B(1) 109.6(6)
C(2)--N(1)--B(2) 111.1(5) C(3)--N(2)--B(3) 109.6(5)
C(3)--N(2)--B(4) 110.4(5) C(4)--N(3)--B(5) 109.8(5)
C(4)--N(3)--B(6) 110.6(5) C(1)--N(1)--C(2) 108.4(5)
C(3)--N(2)--C(3)' 109.1(8) C(4)--N(3)--C(4)' 107.0(8)
.sup.aSymmetry transformations used to generate equivalent atoms: '
= x, -y + 1/2, z
TABLE-US-00017 TABLE 2 Selected Bond Lengths and Angles for
Th(H.sub.3BNMe.sub.2BH.sub.3).sub.2(BH.sub.4).sub.2 Bond Lengths
(.ANG.) Th(1)--B(1) 2.862(10) Th(1)--B(2) 2.862(10) Th(1)--B(3)
2.882(9) Th(1)--B(4) 2.848(9) Th(1)--B(5) 2.608(9) Th(1)--B(6)
2.583(10) B(1)--N(1) 1.546(10) B(2)--N(1) 1.575(10) B(3)--N(2)
1.597(10) B(4)--N(2) 1.569(10) N(1)--C(1) 1.489(8) N(1)--C(2)
1.494(9) N(2)--C(3) 1.483(9) N(2)--C(4) 1.500(7) Bond Angles (deg)
B(1)--Th(1)--B(2) 53.0(3) B(3)--Th(1)--B(4) 53.6(2)
B(5)--Th(1)--B(6) 96.6(3) B(2)--Th(1)--B(3) 100.1(3)
B(1)--Th(1)--B(3) 104.8(3) B(1)--Th(1)--B(4) 143.5(2)
B(1)--Th(1)--B(5) 88.2(3) B(1)--Th(1)--B(6) 114.2(3)
B(2)--Th(1)--B(4) 98.2(3) B(2)--Th(1)--B(5) 141.0(3)
B(2)--Th(1)--B(6) 96.8(3) B(3)--Th(1)--B(5) 92.6(3)
B(3)--Th(1)--B(6) 140.1(3) B(4)--Th(1)--B(5) 118.6(3)
B(4)--Th(1)--B(6) 88.3(3) B(1)--N(1)--B(2) 109.7(6)
B(3)--N(2)--B(4) 109.5(6) C(1)--N(1)--B(1) 109.1(6)
C(1)--N(1)--B(2) 110.7(6) C(2)--N(1)--B(1) 110.0(6)
C(2)--N(1)--B(2) 109.9(6) C(3)--N(2)--B(3) 109.6(6)
C(3)--N(2)--B(4) 108.9(5) C(1)--N(1)--C(2) 107.4(6)
C(3)--N(2)--C(4) 109.6(5)
TABLE-US-00018 TABLE 3 Selected Bond Lengths and Angles for
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3, Structural Isomer A Bond
Lengths (.ANG.) U(1)--B(1) 2.953(4) U(1)--B(2) 2.957(3) U(1)--B(3)
2.939(4) U(1)--B(4) 2.943(3) U(1)--B(5) 2.944(3) U(1)--B(6)
2.949(4) U(1)--H(1D) 2.569(1) U(1)--H(1E) 2.368(1) U(1)--H(2D)
2.424(1) U(1)--H(2E) 2.531(1) U(1)--H(3D) 2.459(1) U(1)--H(3E)
2.438(1) U(1)--H(4D) 2.500(1) U(1)--H(4E) 2.563(1) U(1)--H(5D)
2.518(1) U(1)--H(5E) 2.476(1) U(1)--H(6D) 2.478(1) U(1)--H(6E)
2.599(1) U(1A)--H(6F) 2.496(1) B(1)--N(1) 1.569(8) B(2)--N(1)
1.583(7) B(3)--N(2) 1.581(7) B(4)--N(2) 1.562(8) B(5)--N(3)
1.576(7) B(6)--N(3) 1.562(7) N(1)--C(1) 1.483(7) N(1)--C(2)
1.477(7) N(2)--C(3) 1.491(7) N(2)--C(4) 1.486(7) N(3)--C(5)
1.487(7) N(3)--C(6) 1.490(6) Bond Angles (deg) B(1)--U(1)--B(2)
53.4(2) B(3)--U(1)--B(4) 53.0(2) B(5)--U(1)--B(6) 51.9(2)
B(1)--N(1)--B(2) 109.4(4) B(3)--N(2)--B(4) 109.8(4)
B(5)--N(3)--B(6) 108.8(4) C(1)--N(1)--B(1) 109.1(5)
C(1)--N(1)--B(2) 109.3(2) C(2)--N(1)--B(1) 110.8(4)
C(2)--N(1)--B(2) 109.9(5) C(3)--N(2)--B(3) 109.2(4)
C(3)--N(2)--B(4) 109.9(5) C(4)--N(2)--B(3) 109.4(4)
C(4)--N(2)--B(4) 110.1(4) C(5)--N(3)--B(5) 110.1(4)
C(5)--N(3)--B(6) 110.7(4) C(6)--N(3)--B(5) 108.8(4)
C(6)--N(3)--B(6) 110.3(4) C(1)--N(1)--C(2) 108.3(4)
C(3)--N(2)--C(4) 108.4(4) C(5)--N(3)--C(6) 108.2(4)
TABLE-US-00019 TABLE 4 Selected Bond Lengths and Angles for
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3, Structural Isomer B.sup.a Bond
Lengths (.ANG.) U(1)--B(1) 2.902(6) U(1)--B(2) 2.862(7) U(1)--B(3)
2.861(7) U(1)--B(4) 2.889(6) U(1)--B(5) 2.670(6) U(1)--B(6)'
2.665(6) U(1)--H(11) 2.59(5) U(1)--H(12) 2.46(7) U(1)--H(21)
2.57(6) U(1)--H(22) 2.48(6) U(1)--H(31) 2.46(5) U(1)--H(32) 2.47(5)
U(1)--H(41) 2.47(6) U(1)--H(42) 2.40(5) U(1)--H(51) 2.31(5)
U(1)--H(52) 2.51(5) U(1)--H(53) 2.46(5) B(1)--N(1) 1.581(8)
B(2)--N(1) 1.583(8) B(3)--N(2) 1.593(8) B(4)--N(2) 1.572(7)
B(5)--N(3) 1.540(7) B(6)--N(3) 1.553(7) N(1)--C(1) 1.495(7)
N(1)--C(2) 1.480(7) N(2)--C(3) 1.484(7) N(2)--C(4) 1.473(7)
N(3)--C(5) 1.491(7) N(3)--C(6) 1.484(7) Bond Angles (deg)
B(1)--U(1)--B(2) 53.2(2) B(3)--U(1)--B(4) 53.0(2) B(1)--U(1)--B(4)
104.0(2) B(1)--U(1)--B(5) 139.1(2) B(2)--U(1)--B(5) 86.2(2)
B(3)--U(1)--B(5) 118.3(2) B(4)--U(1)--B(5) 89.8(2) B(1)--N(1)--B(2)
109.2(4) B(3)--N(2)--B(4) 108.4(4) B(5)--N(3)--B(6) 112.7(4)
C(1)--N(1)--B(1) 109.0(5) C(1)--N(1)--B(2) 109.0(5)
C(2)--N(1)--B(1) 109.7(5) C(2)--N(1)--B(2) 110.2(5)
C(3)--N(2)--B(3) 109.4(5) C(3)--N(2)--B(4) 109.4(5)
C(4)--N(2)--B(3) 110.2(5) C(4)--N(2)--B(4) 110.3(5)
C(5)--N(3)--B(5) 108.7(4) C(5)--N(3)--B(6) 109.1(4)
C(6)--N(3)--B(5) 108.2(4) C(6)--N(3)--B(6) 109.3(4)
C(1)--N(1)--C(2) 109.7(5) C(3)--N(2)--C(4) 109.2(5)
C(5)--N(3)--C(6) 108.8(5) .sup.aSymmetry transformations used to
generate equivalent atoms: ' = -x, y + 1/2, -z + 1/2
TABLE-US-00020 TABLE 5 Selected Bond Lengths and Angles for
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).sup.a Bond Lengths (.ANG.)
U(1)--B(1) 2.895(3) U(1)--B(2) 2.901(3) U(1)--H(1A) 2.556(1)
U(1)--H(1B) 2.446(1) U(1)--H(2A) 2.462(1) U(1)--H(2B) 2.547(1)
U(1)--O(1) 2.549(4) B(1)--N(1) 1.582(5) B(2)--N(1) 1.556(5)
N(1)--C(1) 1.484(4) N(1)--C(2) 1.485(4) Bond Angles (deg)
H(1A)--U(1)--H(1B) 44.0(1) H(2A)--U(1)--H(2B) 44.0(1)
B(1)--U(1)--B(2) 52.3(1) B(1)--U(1)--B(1)' 89.5(1)
B(1)--U(1)--B(2)' 138.3(1) B(2)--U(1)--B(1)' 104.2(1)
B(2)--U(1)--B(2)'' 115.4(1) B(1)--N(1)--B(2) 108.9(2)
C(1)--N(1)--B(1) 109.8(3) C(1)--N(1)--B(2) 110.6(3)
C(2)--N(1)--B(1) 109.2(3) C(2)--N(1)--B(2) 109.9(3)
C(1)--N(1)--C(2) 108.4(3) .sup.aSymmetry transformations used to
generate equivalent atoms: ' = -y + 1, z, -x + 1 '' = -z + 1, -x +
1, y
TABLE-US-00021 TABLE 6 Selected Bond Lengths and Angles for
U(H.sub.3BNMe.sub.2BH.sub.3).sub.3(PMe.sub.3).sub.2 Bond Lengths
(.ANG.) U(1)--B(1) 2.953(4) U(1)--B(2) 2.957(3) U(1)--B(3) 2.939(4)
U(1)--B(4) 2.943(3) U(1)--B(5) 2.944(3) U(1)--B(6) 2.949(4)
U(1)--P(1) 3.114(1) U(1)--P(2) 3.109(1) B(1)--N(1) 1.579(4)
B(2)--N(1) 1.569(4) B(3)--N(2) 1.581(4) B(4)--N(2) 1.560(4)
B(5)--N(3) 1.564(4) B(6)--N(3) 1.569(4) N(1)--C(1) 1.489(4)
N(1)--C(2) 1.475(4) N(2)--C(3) 1.481(4) N(2)--C(4) 1.483(3)
N(3)--C(5) 1.485(4) N(3)--C(6) 1.491(4) Bond Angles (deg)
B(1)--U(1)--B(2) 51.2(1) B(3)--U(1)--B(4) 50.9(1) B(5)--U(1)--B(6)
50.9(1) B(3)--U(1)--B(6) 173.1(1) B(5)--U(1)--B(4) 74.0(1)
B(1)--U(1)--B(3) 93.1(1) B(2)--U(1)--B(3) 90.1(1) B(1)--U(1)--B(6)
93.3(1) B(2)--U(1)--B(6) 91.9(1) P(1)--U(1)--P(2) 168.9(1)
P(1)--U(1)--B(1) 69.1(1) P(1)--U(1)--B(2) 120.3(1) P(1)--U(1)--B(3)
93.8(1) P(1)--U(1)--B(4) 83.3(1) P(1)--U(1)--B(5) 84.2(1)
P(1)--U(1)--B(6) 91.0(1) P(2)--U(1)--B(1) 122.0(1) P(2)--U(1)--B(2)
70.7(1) P(2)--U(1)--B(3) 86.4(1) P(2)--U(1)--B(4) 88.3(1)
P(2)--U(1)--B(5) 86.6(1) P(2)--U(1)--B(6) 88.0(1) B(1)--N(1)--B(2)
108.4(2) B(3)--N(2)--B(4) 107.1(2) B(5)--N(3)--B(6) 107.9(2)
C(1)--N(1)--B(1) 108.9(3) C(1)--N(1)--B(2) 110.3(3)
C(2)--N(1)--B(1) 110.3(2) C(2)--N(1)--B(2) 110.5(3)
C(3)--N(2)--B(3) 110.0(3) C(3)--N(2)--B(4) 110.1(3)
C(4)--N(2)--B(3) 110.6(2) C(4)--N(2)--B(4) 110.2(2)
C(5)--N(3)--B(5) 110.2(2) C(5)--N(3)--B(6) 110.8(3)
C(6)--N(3)--B(5) 110.1(2) C(6)--N(3)--B(6) 110.3(2)
C(1)--N(1)--C(2) 108.4(3) C(3)--N(2)--C(4) 108.8(2)
C(5)--N(3)--C(6) 107.7(3)
TABLE-US-00022 TABLE 7 Selected Bond Lengths and Angles for
La(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf).sup.a Bond Lengths (.ANG.)
La(1)--B(1) 2.96(1) La(1)--B(2) 2.93(1) La(1)--H(1A) 2.683(1)
La(1)--H(1B) 2.438(1) La(1)--H(2A) 2.583(1) La(1)--H(2B) 2.480(1)
La(1)--O(1) 2.51(1) B(1)--N(1) 1.54(1) B(2)--N(1) 1.57(1)
N(1)--C(1) 1.50(1) N(1)--C(2) 1.46(1) Bond Angles (deg)
H(1A)--La(1)--H(1B) 42.7(1) H(2A)--La(1)--H(2B) 43.5(1)
B(1)--La(1)--B(2) 51.3(3) B(1)--La(1)--B(1)' 89.1(3)
B(1)--La(1)--B(2)' 136.1(3) B(2)--La(1)--B(1)' 106.0(3)
B(2)--La(1)--B(2)'' 115.7(2) B(1)--N(1)--B(2) 109.9(7)
C(1)--N(1)--B(1) 111.2(8) C(1)--N(1)--B(2) 110.6(8)
C(2)--N(1)--B(1) 105.4(9) C(2)--N(1)--B(2) 112.1(9)
C(1)--N(1)--C(2) 107.6(7) .sup.aSymmetry transformations used to
generate equivalent atoms: ' = -z + 1, -x + 1, y '' = -y + 1, z, -x
+ 1
TABLE-US-00023 TABLE 8 Selected Bond Lengths and Angles for
Sm(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) Bond Lengths (.ANG.)
Sm(1)--O(1) 2.468(2) Sm(1)--B(1) 2.843(4) Sm(1)--B(2) 2.842(3)
Sm(1)--B(3) 2.851(4) Sm(1)--B(4) 2.853(4) Sm(1)--B(5) 2.833(4)
Sm(1)--B(6) 2.876(4) B(1)--N(1) 1.558(5) B(2)--N(1) 1.567(5)
B(3)--N(2) 1.583(6) B(4)--N(2) 1.569(6) B(5)--N(3) 1.555(5)
B(6)--N(3) 1.574(5) N(1)--C(1) 1.485(4) N(1)--C(2) 1.475(4)
N(2)--C(3) 1.474(4) N(2)--C(4) 1.471(5) N(3)--C(5) 1.491(4)
N(3)--C(6) 1.483(4) Bond Angles (deg) B(1)--Sm(1)--B(2) 53.0(1)
B(3)--Sm(1)--B(4) 53.0(1) B(5)--Sm(1)--B(6) 52.9(1)
B(1)--N(1)--B(2) 108.4(2) B(3)--N(2)--B(4) 107.6(3)
B(5)--N(3)--B(6) 108.6(2) C(1)--N(1)--B(1) 110.5(3)
C(1)--N(1)--B(2) 109.8(3) C(2)--N(1)--B(1) 109.9(3)
C(2)--N(1)--B(2) 109.4(3) C(3)--N(2)--B(3) 110.3(3)
C(3)--N(2)--B(4) 110.4(3) C(4)--N(2)--B(3) 109.1(3)
C(4)--N(2)--B(4) 111.0(3) C(5)--N(3)--B(5) 110.7(3)
C(5)--N(3)--B(6) 110.5(3) C(6)--N(3)--B(5) 109.1(3)
C(6)--N(3)--B(6) 109.6(3) C(1)--N(1)--C(2) 108.9(3)
C(3)--N(2)--C(4) 108.4(3) C(5)--N(3)--C(6) 108.2(3)
TABLE-US-00024 TABLE 9 Selected Bond Lengths and Angles for
Eu(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) Bond Lengths (.ANG.)
Eu(1)--O(1) 2.468(3) Eu(1)--B(1) 2.851(7) Eu(1)--B(2) 2.863(7)
Eu(1)--B(3) 2.854(7) Eu(1)--B(4) 2.886(7) Eu(1)--B(5) 2.851(7)
Eu(1)--B(6) 2.838(6) B(1)--N(1) 1.593(8) B(2)--N(1) 1.593(8)
B(3)--N(2) 1.549(7) B(4)--N(2) 1.578(7) B(5)--N(3) 1.581(7)
B(6)--N(3) 1.553(7) N(1)--C(1) 1.474(6) N(1)--C(2) 1.483(6)
N(2)--C(3) 1.498(6) N(2)--C(4) 1.486(6) N(3)--C(5) 1.481(6)
N(3)--C(6) 1.499(6) Bond Angles (deg) B(1)--Eu(1)--B(2) 53.6(2)
B(3)--Eu(1)--B(4) 52.7(2) B(5)--Eu(1)--B(6) 53.2(2)
B(1)--N(1)--B(2) 108.2(4) B(3)--N(2)--B(4) 109.2(4)
B(5)--N(3)--B(6) 108.8(4) C(1)--N(1)--B(1) 110.3(5)
C(1)--N(1)--B(2) 109.8(5) C(2)--N(1)--B(1) 109.8(5)
C(2)--N(1)--B(2) 111.2(5) C(3)--N(2)--B(3) 109.9(4)
C(3)--N(2)--B(4) 111.3(4) C(4)--N(2)--B(3) 108.9(4)
C(4)--N(2)--B(4) 109.0(5) C(5)--N(3)--B(5) 109.9(4)
C(5)--N(3)--B(6) 110.5(4) C(6)--N(3)--B(5) 109.7(4)
C(6)--N(3)--B(6) 110.0(4) C(1)--N(1)--C(2) 107.7(5)
C(3)--N(2)--C(4) 108.4(4) C(5)--N(3)--C(6) 108.0(4)
TABLE-US-00025 TABLE 10 Selected Bond Lengths and Angles for
Er(H.sub.3BNMe.sub.2BH.sub.3).sub.3(thf) Bond Lengths (.ANG.)
Er(1)--O(1) 2.417(3) Er(1)--B(1) 2.815(5) Er(1)--B(2) 2.786(6)
Er(1)--B(3) 2.775(7) Er(1)--B(4) 2.820(6) Er(1)--B(5) 2.763(5)
Er(1)--B(6) 2.856(6) B(1)--N(1) 1.572(7) B(2)--N(1) 1.577(6)
B(3)--N(2) 1.570(8) B(4)--N(2) 1.586(8) B(5)--N(3) 1.568(6)
B(6)--N(3) 1.592(6) N(1)--C(1) 1.485(6) N(1)--C(2) 1.494(6)
N(2)--C(3) 1.490(7) N(2)--C(4) 1.489(6) N(3)--C(5) 1.489(6)
N(3)--C(6) 1.489(6) Bond Angles (deg) B(1)--Er(1)--B(2) 53.9(2)
B(3)--Er(1)--B(4) 53.7(2) B(5)--Er(1)--B(6) 53.6(2)
B(1)--N(1)--B(2) 107.5(3) B(3)--N(2)--B(4) 106.5(4)
B(5)--N(3)--B(6) 106.8(4) C(1)--N(1)--B(1) 110.7(4)
C(1)--N(1)--B(2) 109.7(4) C(2)--N(1)--B(1) 109.9(4)
C(2)--N(1)--B(2) 110.4(4) C(3)--N(2)--B(3) 110.9(4)
C(3)--N(2)--B(4) 110.8(5) C(4)--N(2)--B(3) 111.0(4)
C(4)--N(2)--B(4) 109.6(4) C(5)--N(3)--B(5) 110.0(4)
C(5)--N(3)--B(6) 110.1(4) C(6)--N(3)--B(5) 110.3(4)
C(6)--N(3)--B(6) 111.2(4) C(1)--N(1)--C(2) 108.6(4)
C(3)--N(2)--C(4) 108.1(4) C(5)--N(3)--C(6) 108.5(4)
TABLE-US-00026 TABLE 11 Selected Bond Lengths and Angles for
Eu.sub.2(H.sub.3BNMe.sub.2BH.sub.3).sub.4(thf).sub.4.sup.a Bond
Lengths (.ANG.) Eu(1)--O(1) 2.582(2) Eu(1)--O(2) 2.605(2)
Eu(1)--B(1) 2.885(4) Eu(1)--B(2) 3.127(4) Eu(1)--B(3) 2.991(4)
Eu(1)--B(4) 3.215(6) Eu(1)'--B(4) 2.975(4) B(1)--N(1) 1.582(4)
B(2)--N(1) 1.579(4) B(3)--N(2) 1.570(4) B(4)--N(2) 1.571(4)
N(1)--C(1) 1.468(4) N(1)--C(2) 1.480(4) N(2)--C(3) 1.481(5)
N(2)--C(4) 1.484(5) Bond Angles (deg) O(1)--Eu(1)--O(2) 167.9(1)
B(2)--Eu(1)--B(4) 173.8(1) B(1)--Eu(1)--B(4) 132.0(1)
B(2)--Eu(1)--B(3) 133.9(1) B(1)--Eu(1)--B(2) 51.1(1)
B(3)--Eu(1)--B(4) 49.3(1) O(1)--Eu(1)--B(1) 96.1(1)
O(1)--Eu(1)--B(2) 87.4(1) O(1)--Eu(1)--B(3) 96.2(1)
O(1)--Eu(1)--B(4) 87.0(1) O(2)--Eu(1)--B(1) 93.5(1)
O(2)--Eu(1)--B(2) 93.1(1) O(2)--Eu(1)--B(3) 92.2(1)
O(2)--Eu(1)--B(4) 92.0(1) B(1)--N(1)--B(2) 110.9(2)
B(3)--N(2)--B(4) 111.6(4) C(1)--N(1)--B(1) 109.8(3)
C(1)--N(1)--B(2) 110.3(3) C(2)--N(1)--B(1) 109.0(3)
C(2)--N(1)--B(2) 109.1(3) C(3)--N(2)--B(3) 108.8(4)
C(3)--N(2)--B(4) 109.3(4) C(4)--N(2)--B(3) 109.1(4)
C(4)--N(2)--B(4) 109.3(4) C(1)--N(1)--C(2) 107.7(3)
C(3)--N(2)--C(4) 108.8(4) .sup.aSymmetry transformations used to
generate equivalent atoms: ' = -x + 1, -y + 1, -z
STATEMENTS REGARDING INCORPORATION BY REFERENCE AND VARIATIONS
[0694] All references throughout this application, for example
patent documents including issued or granted patents or
equivalents; patent application publications; and non-patent
literature documents or other source material; are hereby
incorporated by reference herein in their entireties, as though
individually incorporated by reference, to the extent each
reference is at least partially not inconsistent with the
disclosure in this application (for example, a reference that is
partially inconsistent is incorporated by reference except for the
partially inconsistent portion of the reference).
[0695] The terms and expressions which have been employed herein
are used as terms of description and not of limitation, and there
is no intention in the use of such terms and expressions of
excluding any equivalents of the features shown and described or
portions thereof, but it is recognized that various modifications
are possible within the scope of the invention claimed. Thus, it
should be understood that although the present invention has been
specifically disclosed by preferred embodiments, exemplary
embodiments and optional features, modification and variation of
the concepts herein disclosed may be resorted to by those skilled
in the art, and that such modifications and variations are
considered to be within the scope of this invention as defined by
the appended claims. The specific embodiments provided herein are
examples of useful embodiments of the present invention and it will
be apparent to one skilled in the art that the present invention
may be carried out using a large number of variations of the
devices, device components, methods steps set forth in the present
description. As will be obvious to one of skill in the art, methods
and devices useful for the present methods can include a large
number of optional composition and processing elements and
steps.
[0696] When a group of substituents is disclosed herein, it is
understood that all individual members of that group and all
subgroups, including any isomers, enantiomers, and diastereomers of
the group members, are disclosed separately. When a Markush group
or other grouping is used herein, all individual members of the
group and all combinations and subcombinations possible of the
group are intended to be individually included in the disclosure.
When a compound is described herein such that a particular isomer,
enantiomer or diastereomer of the compound is not specified, for
example, in a formula or in a chemical name, that description is
intended to include each isomers and enantiomer of the compound
described individual or in any combination. Additionally, unless
otherwise specified, all isotopic variants of compounds disclosed
herein are intended to be encompassed by the disclosure. For
example, it will be understood that any one or more hydrogens in a
molecule disclosed can be replaced with deuterium or tritium.
Isotopic variants of a molecule are generally useful as standards
in assays for the molecule and in chemical and biological research
related to the molecule or its use. Methods for making such
isotopic variants are known in the art. Specific names of compounds
are intended to be exemplary, as it is known that one of ordinary
skill in the art can name the same compounds differently.
[0697] Many of the molecules disclosed herein contain one or more
ionizable groups [groups from which a proton can be removed (e.g.,
--COON) or added (e.g., amines) or which can be quaternized (e.g.,
amines)]. All possible ionic forms of such molecules and salts
thereof are intended to be included individually in the disclosure
herein. With regard to salts of the compounds herein, one of
ordinary skill in the art can select from among a wide variety of
available counterions those that are appropriate for preparation of
salts of this invention for a given application. In specific
applications, the selection of a given anion or cation for
preparation of a salt may result in increased or decreased
solubility of that salt.
[0698] Every formulation or combination of components described or
exemplified herein can be used to practice the invention, unless
otherwise stated.
[0699] Whenever a range is given in the specification, for example,
a temperature range, a time range, or a composition or
concentration range, all intermediate ranges and subranges, as well
as all individual values included in the ranges given are intended
to be included in the disclosure. It will be understood that any
subranges or individual values in a range or subrange that are
included in the description herein can be excluded from the claims
herein.
[0700] All patents and publications mentioned in the specification
are indicative of the levels of skill of those skilled in the art
to which the invention pertains. References cited herein are
incorporated by reference herein in their entirety to indicate the
state of the art as of their publication or filing date and it is
intended that this information can be employed herein, if needed,
to exclude specific embodiments that are in the prior art. For
example, when composition of matter are claimed, it should be
understood that compounds known and available in the art prior to
Applicant's invention, including compounds for which an enabling
disclosure is provided in the references cited herein, are not
intended to be included in the composition of matter claims
herein.
[0701] As used herein, "comprising" is synonymous with "including,"
"containing," or "characterized by," and is inclusive or open-ended
and does not exclude additional, unrecited elements or method
steps. As used herein, "consisting of" excludes any element, step,
or ingredient not specified in the claim element. As used herein,
"consisting essentially of" does not exclude materials or steps
that do not materially affect the basic and novel characteristics
of the claim. In each instance herein any of the terms
"comprising", "consisting essentially of" and "consisting of" may
be replaced with either of the other two terms. The invention
illustratively described herein suitably may be practiced in the
absence of any element or elements, limitation or limitations which
is not specifically disclosed herein.
[0702] One of ordinary skill in the art will appreciate that
starting materials, biological materials, reagents, synthetic
methods, purification methods, analytical methods, assay methods,
and biological methods other than those specifically exemplified
can be employed in the practice of the invention without resort to
undue experimentation. All art-known functional equivalents, of any
such materials and methods are intended to be included in this
invention. The terms and expressions which have been employed are
used as terms of description and not of limitation, and there is no
intention that in the use of such terms and expressions of
excluding any equivalents of the features shown and described or
portions thereof, but it is recognized that various modifications
are possible within the scope of the invention claimed. Thus, it
should be understood that although the present invention has been
specifically disclosed by preferred embodiments and optional
features, modification and variation of the concepts herein
disclosed may be resorted to by those skilled in the art, and that
such modifications and variations are considered to be within the
scope of this invention as defined by the appended claims.
* * * * *