U.S. patent application number 14/191730 was filed with the patent office on 2014-08-28 for volatile imidazoles and group 2 imidazole based metal precursors.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. The applicant listed for this patent is AIR PRODUCTS AND CHEMICALS, INC.. Invention is credited to Moo-Sung Kim, John Anthony Thomas Norman, Melanie K. Perez.
Application Number | 20140242795 14/191730 |
Document ID | / |
Family ID | 43754903 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140242795 |
Kind Code |
A1 |
Norman; John Anthony Thomas ;
et al. |
August 28, 2014 |
Volatile Imidazoles and Group 2 Imidazole Based Metal
Precursors
Abstract
Sterically hindered imidazolate ligands are described, along
with their synthesis, which are capable of coordinating to Group 2
metals, such as: calcium, magnesium, strontium, in an eta-5
coordination mode which permits the formation of monomeric or
dimeric volatile complexes. A compound comprising one or more
polysubstituted imidazolate anions coordinated to a metal selected
from the group consisting of barium, strontium, magnesium, radium
or calcium or mixtures thereof. Alternatively, one anion can be
substituted with and a second non-imidazolate anion. Synthesis of
the novel compounds and their use to form BST films is also
contemplated
Inventors: |
Norman; John Anthony Thomas;
(Encinitas, CA) ; Perez; Melanie K.; (San Diego,
CA) ; Kim; Moo-Sung; (Sungnam, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIR PRODUCTS AND CHEMICALS, INC. |
Allentown |
PA |
US |
|
|
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
43754903 |
Appl. No.: |
14/191730 |
Filed: |
February 27, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13016127 |
Jan 28, 2011 |
8703103 |
|
|
14191730 |
|
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|
61301824 |
Feb 5, 2010 |
|
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61369448 |
Jul 30, 2010 |
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Current U.S.
Class: |
438/681 ;
423/598 |
Current CPC
Class: |
C07D 233/54 20130101;
H01L 21/28556 20130101 |
Class at
Publication: |
438/681 ;
423/598 |
International
Class: |
H01L 21/285 20060101
H01L021/285 |
Claims
1. A method of depositing a metal containing film comprising
reacting an imidazolate structure selected from the group
consisting of: ##STR00008## wherein R.sup.1, R.sup.2, R.sup.3 and
are each individually bulky groups selected from the group
consisting of: C.sub.1-C.sub.10 tertiary alkyl; C.sub.1-C.sub.10
tertiary alkoxy; C.sub.1-C.sub.10 tertiary alkylamine;
C.sub.1-C.sub.10 tertiary alkyl functionalized with a heteroatom
substituted ring structure; C.sub.1-C.sub.10 tertiary alkyl
functionalized with an amide group; C.sub.1-C.sub.10 tertiary alkyl
functionalized with an ester group, and mixtures thereof; (L) is a
neutral ligand selected from the group consisting of aliphatic
C.sub.3-C.sub.20 ether or polyether, crown ether, amine, poly
amine, amide, poly amide, ester, polyester, aromatic ether,
aromatic ester, aromatic amide, aromatic amine, pyridine,
imidazole, pyridine, pyrazine, furan, pyrrole, and mixtures
thereof; n=0-4; and M=Ba, Sr, Ca, Ra, Mg, or mixtures thereof, with
an oxidant selected from the group consisting of water, alcohol,
oxygen, ozone, nitrous oxide, nitrogen dioxide, hydrogen peroxide,
or combinations thereof either in the presence or absence of an
applied plasma discharge to grow a metal-containing film selected
from the group consisting of barium oxide, strontium oxide,
magnesium oxide, calcium oxide or radium oxide and mixtures
thereof, using a reactor pressure between 0.001-1000 Torr and a
temperature from 0-1000.degree. C.
2. The method of claim 1 wherein the metal-containing film is
barium oxide grown at a rate of >1 Angstrom per cycle.
3. The method of claim 2 where the rate >1.5 Angstrom per
cycle.
4. The method of claim 3 where the rate is >2 Angstrom per
cycle.
5. The method of claim 1 where the metal-containing film is
strontium oxide grown at a rate of >1 Angstrom per cycle.
6. The method of claim 5 where the rate is >1.5 Angstrom per
cycle.
7. The method of claim 6 where the rate is >2 Angstrom per
cycle.
8. The method of claim 1 wherein the compound is selected from the
group consisting of: Di-barium
tetra(2,4,5-tris-t-butylimidazolate); Di-barium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and
Di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
9. The method of claim 1 wherein the compound is selected from the
group consisting of: Di-strontium
tetra(2,4,5-tris-t-butylimidazolate); Di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and,
Di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
10. The method of claim 1 wherein R.sup.1, R.sup.2, and R.sup.3 of
each imidazolate anion are the same bulky group.
11. The method of claim 1 wherein at least one of R.sup.1, R.sup.2,
and R.sup.3 of one imidazolate anion is joined to at least one of
the R.sup.1, R.sup.2, and R.sup.3 of another imidazolate anion to
connect the two imidazolate anions.
12. A method of forming a barium strontium titanium film, a
strontium titanium film, or a barium titanium film, comprising
reacting an imidazolate structure selected from the group
consisting of: ##STR00009## wherein R.sup.1, R.sup.2, R.sup.3 and
are each individually bulky groups selected from the group
consisting of: C.sub.1-C.sub.10 tertiary alkyl; C.sub.1-C.sub.10
tertiary alkoxy; C.sub.1-C.sub.10 tertiary alkylamine;
C.sub.1-C.sub.10 tertiary alkyl functionalized with a heteroatom
substituted ring structure; C.sub.1-C.sub.10 tertiary alkyl
functionalized with an amide group; C.sub.1-C.sub.10 tertiary alkyl
functionalized with an ester group, and mixtures thereof; (L) is a
neutral ligand selected from the group consisting of aliphatic
C.sub.3-C.sub.20 ether or polyether, crown ether, amine, poly
amine, amide, poly amide, ester, polyester, aromatic ether,
aromatic ester, aromatic amide, aromatic amine, pyridine,
imidazole, pyridine, pyrazine, furan, pyrrole, and mixtures
thereof; n=0-4; and M=Ba, Sr or mixtures thereof, with alternating
pulses of titanium precursors selected from the group consisting of
titanium alkoxide, titanium alkoxide/diketonate, titanium
cyclopentadienyl, titanium amide, titanium imidazolate and mixtures
thereof in an ALD or pulsed CVD mode to grow the barium strontium
titanium film.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a divisional application of U.S.
patent application Ser. No. 13/016,127, filed on Jan. 28, 2011,
which claims the benefit of prior U.S. Provisional Patent
Application Ser. No. 61/301,824 filed on Feb. 5, 2010 and
61/369,448 filed on Jul. 30, 2010, the disclosures of which are
incorporated herein in their entirety.
BACKGROUND OF THE INVENTION
[0002] The semiconductor fabrication industry continues to source
volatile metal containing precursors for vapor deposition
processes, including chemical vapor deposition (CVD) and atomic
layer deposition (ALD), for fabricating conformal metal containing
films on substrates, such as silicon, metal nitride, metal oxide
and other metal-containing layers, using these metal-containing
precursors.
[0003] Barium and strontium containing precursors are especially
sought after for the deposition of thin barium and strontium oxide
containing thin films, such as: strontium titanate (STO) and barium
strontium titanate oxide (BST) for advanced memory device
manufacture. Strontium precursors are also useful for the thin film
deposition of ferroelectric materials of the type
SrBi.sub.2Ta.sub.2O.sub.9 for non-volatile memory, for the
fabrication of thin film high temperature (Tc) superconductors of
the type Bi.sub.2Sr.sub.2Ca.sub.n-1Cu.sub.nO.sub.5+(2n-1)d and for
the manufacture of SrS:Ce and SrS:Cu phosphors for
electroluminescent displays. Although there are fluorinated barium
precursors which have excellent volatility, their use for BST
manufacturing is effectively precluded, since fluoride ion can form
in the oxide film and act as a charge carrier, which degrades the
dielectric constant of the oxide film. Numerous strontium sources
for strontium oxide and strontium titanate exist, but none have the
ALD performance of the precursors of this disclosure.
[0004] Thus, there is a strong need for volatile unfluorinated
barium and strontium precursor compounds with high ALD performance,
but such compounds are scarce, especially so for barium. This stems
from the large ionic radius of the barium +2 and strontium +2 ions
requiring ionic ligands which can provide a coordinating
environment sufficient to provide compounds which are monomeric or
dimeric in strontium or barium. If this requirement is not met, the
strontium, and especially the barium compounds tend to form highly
associated or polymeric structures of limited volatility. However,
even if monomeric or dimeric structures can be achieved, they may
still not possess the thermal stability required to survive the
high sublimation or distillation temperatures required for their
vaporization and to maintain their thermal stability when adsorbed
as monolayers in ALD. For all of these reasons, unfluorinated
barium and strontium precursors, which are monomeric or dimeric,
thermally stable, readily volatile and highly suited to BST and STO
manufacture by ALD or CVD, are extremely scarce but highly sought
after. Even more sought after are group 2 volatile precursors which
have high deposition rates in ALD.
[0005] The prior art has attempted to provide precursors for these
applications, as set forth below. However, none of the metal
complexes in the prior art share the special characteristic of the
complexes disclosed in the present invention. The compounds
disclosed herein are exceptional in their volatility and thermal
stability under conditions of vaporization. In addition, they have
exceptionally high ALD deposition rates enabling them to grow 1
monolayer of metal oxide per ALD cycle. This makes them highly
effective as precursors for STO and BST film growth and any other
application which requires volatile sources of barium, strontium,
magnesium, radium or calcium precursors.
[0006] Barium and other alkaline earth metal diketiminates are
described in the literature. For beta-diketonates the compound
[Ba(THD).sub.2].sub.4 (where THD is
3,3,5,5-tetramethylheptanedionate) has been reported. Although it
is a stable and volatile compound, its molecular weight of >2000
renders its utility in ALD or CVD process challenging, especially
when compared to smaller, more volatile, compounds, such as the
barocenes and especially when compared to the new compounds of the
present invention, which are more cleanly volatile and have higher
ALD deposition rates and lowered melting points when compared to
the barocenes.
[0007] Thermally stable and volatile tri(pyrazoyl)borate alkaline
earth complexes, including those of barium have been reported.
However, these compounds suffer from containing the element boron,
which under oxidation conditions, deposits boron oxide into the
metal oxide of a CVD or ALD process.
[0008] Volatile barium and strontium complexes based on
diketiminate ligands bearing NMe.sub.2 groups substituted on the
core diimine nitrogens are reported. But the barium molecule in
this series sublimed to give only a 79% sublimation recovery
leaving a 14 wt % involatile residue. This sublimation was
performed at 0.05 Torr. If it had been conducted at atmospheric
pressure, its involatile residue would have been significantly
higher. These results indicate this molecule to have limited
suitability as a precursor for CVD or ALD processes.
[0009] The synthesis and thermal properties of a series of nine
different barium cyclopentadienyl, also known as barocenes', have
been reported. Selected species from these barocenes, particularly
the barium bis(tri-tert-butlycyclopentadienyl), are `state of the
art` precursors possesing an attractive combination of thermal
stability and volatility. However, the new molecules of the present
invention are shown to be superior to them with regard to these two
key properties. Additionally, the new precursors of this
disclosure, due to their unique molecular characteristics, also
have exceptionally high ALD deposition rates making them more
attractive from a device manufacturing perspective.
[0010] Other references of interest include: [0011] WO 2009/086263.
[0012] J. Norman, G. Pez, J. Chem. Soc. Chem. Commun., 971, (1991)
[0013] Harder, S. (2002); "Homoleptic beta Diketiminate Complexes
of the Alkaline Earth Metals: Trends in the Series Mg, Ca, Sr, and
Ba"; Organometallics 21(18), 3782-3787. [0014] U.S. Pat. No.
5,319,118 [0015] El-Kaderi, H. M. and M. J. W. Heeg, C. H.; (2004).
"Sandwich Complexes of the Heavier Alkaline Earth Metals Containing
5-Diketiminato Ligand Sets." Organometallics 23: 4995-5002. [0016]
M. J. Saly, M. J. Heeg and C. Winters, Inorganic Chemistry,
publication date (Web) Apr. 27, 2009. [0017] B. Sedai, M. J. Heeg
and C. Winter, Organometallics, 2009, 18 (4) p 1032-1038. [0018]
Timo Hatanpaa, Marko Vehkamaki, Ilpo Mutikainen, Jarno Kansikas and
Mikko Ritala "Synthesis and characterization of cyclopentadienyl
complexes of barium: precursors for atomic layer deposition of
BaTiO.sub.3" Dalton Trans., 2004, p. 1181-1188. [0019] J. Zhang, X.
Chen, Chem. Comm. 1689-1699 (2006). [0020] H. A. Every, T. A.
Zawodzinski, Electrochemical Society Proceedings, 277-286, Volume
21 (2001).
BRIEF SUMMARY OF THE INVENTION
[0021] Sterically hindered imidazole ligands are disclosed, along
with the syntheses of the same, which when complexed to a Group 2
metal, form highly volatile and stable complexes that are
exceptionally useful as precursor molecules for CVD, ALD and the
like thin film deposition processes.
[0022] The present invention is an imidazole molecule which can be
deprotonated to yield an imidazolate substituted in at least the
2,5-positions with a bulky group, R, of the formula:
##STR00001##
[0023] wherein R.sup.1 and R.sup.3 are individually bulky groups
having sufficient 3-dimensional form to impart a property to the
imidazolate to bond with metals in an eta1, eta-2, eta-3, eta-4 or
eta-5 bond; and R.sub.2 can be a bulky group or a group which is
not a bulky group.
[0024] Preferably, the imidazolate's R.sub.1 and R.sub.3 are
individually selected from the group consisting of tert-butyl,
isopropyl, tert-amyl, neopentyl, adamantly, hexyl, cyclohexyl,
propyl, butyl, isobutyl, pentyl, isopentyl, neopenty, norbornyl,
bicyclo[2.2.1]heptyl, dimethylpropyl, dimethylbutyl,
dimethylpentyl, dimethylhexyl, ethylmethylpropyl, isohexyl,
isopentyl
[0025] Preferably, the imidazolate's R.sub.2 is a bulky group.
[0026] Preferably, the imidazolate comprises
2,4,5-tris-t-butylimidazolate.
[0027] In another aspect, the present invention teaches compounds
comprising one or more polysubstituted imidazolate anions
coordinated to a metal selected from the group consisting of
barium, strontium, magnesium, calcium or radium or mixtures
thereof. Mixtures of these novel imidazolate metal complexes
combined with other metal complexes are also contemplated where the
additional metal complex can be a titanium imidazolate complex or a
non-imidazolate complex including where the complexes are dissolved
in a solvent and the resulting formulation used in DLI mode.
Particularly useful combinations would include those where a
strontium imidazole is combined with a titanium complex as a simple
mixture or co-dissolved in a suitable solvent as a DLI formulation
for STO ALD or CVD. Similarly, barium imidazolate complexes can be
combined with suitable titanium complexes for BST film growth.
[0028] Alternatively, one imidazolate anion can be substituted with
a second non-imidazolate anion. In addition, the imidazolate anion
may also bear a substituent, which is also deprotonated to yield a
dianionic species, and this dianion is coordinated to a metal, such
as barium, strontium, magnesium, calcium or radium or mixtures
thereof.
[0029] Preferably, the second non-imidazolate anion is selected
from the group consisting of polysubstituted imidazolate anion,
polyalkylated pyrrolyl anion, beta-diketonates, acetates,
ketoiminates, diimines, alkoxides, amides, hydrides,
beta-ketoesters, amidinates, guanidinates, cyclopentadienyl,
cyanide, isocyanide, formate, oxalate, malonate, phenoxide,
thiolate, sulfide, nitrate, alkyl, silylalkyl, fluoroalkyl, aryl,
imidazolate, hydride and mixtures thereof.
[0030] Synthesis of the novel compounds and their use to form BST
films is also contemplated.
[0031] Most preferably, the imidazolate is: [0032]
2,4,5-tri-tert-butylimidazolate [0033]
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate [0034]
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate [0035]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate; and
their barium, strontium, magnesium and calcium salts.
[0036] An embodiment of the present invention's imidazolate
comprises a mixture of strontium imidazolate with a volatile
titanium source. More preferably, this embodiment includes as the
volatile titanium source an imidazolate based titanium
precursor
[0037] Alternatively, in the imidazole, R.sup.1, R.sup.2 and
R.sup.3 are linked together to form a cyclic structure.
[0038] Alternately, the imidazole has at least two of R.sup.1,
R.sup.2 and R.sup.3 joined so that two or more imidazole ligands
are joined together.
[0039] Preferred metal imidazolates include; Di-barium
tetra(2,4,5-tris-t-butylimidazolate); Di-barium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-barium tetra(2-(1,1-dim
ethylbutyl)-4,5-di-tert-butylimidazolate); and, Di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazol-
ate); Di-strontium tetra(2,4,5-tris-t-butylimidazolate);
Di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and,
Di-strontium tetra(2-(1,1-dim
ethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
[0040] Preferably, the present invention's metal imidazolates are
contained in a stainless steel container. More preferably, the
stainless steel container is electropolished in its interior. Most
preferably, the stainless steel container is outfitted with inlet
and outlet valves for high purity, low dead space service.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0041] FIG. 1 is an illustration of the X-ray structure of
2,5-di-tert-butylimidazole.
[0042] FIG. 2 is an illustration of the X-ray structure of
2,4,5-tri-tert-butylimidazole (hydrogen atoms are not illustrated
for purposes of clarity except on N(1)).
[0043] FIG. 3 is an illustration of the structure of barium
bis(2,4,5-tri-tert-butylimidazolate)(tetrahydrofuran) (hydrogen
atoms are not illustrated for purposes of clarity).
[0044] FIG. 4 is an illustration of di-barium
tetra(2,4,5-tri-tert-butylimidazolate) (hydrogen atoms are not
illustrated for purposes of clarity).
[0045] FIG. 5 is the thermogravimetric analysis (TGA)/differential
scanning calorimetry (DSC) result for di-barium
tetra(2,4,5-tri-tert-butylimidazolate), wherein the TGA is a solid
line and the DSC is a dashed line.
[0046] FIG. 6 is an illustration of di-strontium
tetra(2,4,5-tri-tert-butylimidazolate) (hydrogen atoms are not
illustrated for purposes of clarity).
[0047] FIG. 7 is the TGA/DSC of di-strontium
tetra(2,4,5-tri-tert-butylimidazolate), wherein the TGA is a solid
line and the DSC is a dashed line.
[0048] FIG. 8 is an illustration of di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl)imidazolate(hydrogen
atoms are not illustrated for purposes of clarity).
[0049] FIG. 9 is the TGA/DSC result for di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl)imidazolate), wherein
the TGA is a solid line and the DSC is a dashed line.
[0050] FIG. 10 is an illustration of di-barium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl)imidazolate) (hydrogen
atoms are not illustrated for purposes of clarity).
[0051] FIG. 11 is the DSC result for di-barium
tetra(2-tert-butyl-4,5-di(1,1-dim ethylpropyl)imidazolate).
[0052] FIG. 12 is the TGA results for di-barium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl)imidazolate).
[0053] FIG. 13 is an illustration of di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butyl)imidazolate)
(hydrogen atoms are not illustrated for purposes of clarity).
[0054] FIG. 14 is the TGA/DSC result for di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butyl)imidazolate), wherein
the TGA is a solid line and the DSC is a dashed line.
[0055] FIG. 15 is an illustration of di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butyl)imidazolate)
(hydrogen atoms are not illustrated for purposes of clarity).
[0056] FIG. 16 is the TGA/DSC result for di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butyl)imidazolate), wherein
the TGA is a solid line and the DSC is a dashed line.
[0057] FIG. 17 is the TGA/DSC result for
di-barium-tetra(2-(1,1-dimethylbutyl)-4,5-di(1,1-dimethylpropyl)imidazola-
te), wherein the TGA is a solid line and the DSC is a dashed
line.
[0058] FIG. 18 illustrates the ALD strontium oxide film thickness
as a function of the number of ALD cycles for the precursor
di-strontium tetra(2-tert-butyl-4,5-di-(1,1-dim
ethylpropyl)imidazolate) reacted with ozone.
[0059] FIG. 19 illustrates the ALD saturation curve for a
di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate)/ozone
ALD process at 350.degree. C. substrate temperature.
[0060] FIG. 20 illustrates the transmission electron microscopy
(TEM) of an ALD SrO film grown from di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate) at
375.degree. C., capped with 3.3 nm of titanium dioxide.
[0061] FIG. 21 illustrates the X-ray Photoelectron Spectroscopy
(XPS) analysis of an SrO film grown at 350 C using di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate)/ozone.
[0062] FIG. 22 illustrates the thermal stability of di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate).
DETAILED DESCRIPTION OF THE INVENTION
[0063] Currently, a major use of ALD in the semiconductor industry
is the growth of metal oxides, such as: strontium oxide, barium
oxide and the perovskite oxides: strontium titanate (STO) and
barium titanate (BST). Often, these processes are required to grow
perfectly conformal films into deeply bored cyclindrical volumes
(vias) or over columnar structures (pillars), where it is
imperative that there is no thermal decomposition or CVD component
that will degrade conformality.
[0064] One major mechanism by which precursors thermally degrade is
when the anionic ligand to which the metal coordinates starts to
decompose. Thus, making metal precursors which are coordinated to
anions which are thermally robust is highly desirable. The novel
imidazolate ligand anions of this disclosure are demonstrated to be
of high thermal stability. Also, it is important that in the
evaporation phase the anionic ligand does not coordinate to
multiple metal centers to form compounds of high nuclearity, such
as; tetramers or polymers, which are either of low volatility or
are involatile. So, in summation, the anionic ligands need to
coordinate a relatively low number of metal centers, such as; 1, 2
or 3 and are thermally very resilient against degradation.
[0065] However, notwithstanding this need for high thermal
stability, the precursors also need to be chemically highly
reactive under ALD conditions. To achieve such a highly stable
anionic ligand also means that its formal negative charge needs to
be stabilized by the structure of the ligand. The novel imidazolate
anions of this disclosure stabilize their negative charge by being
a five membered ring aromatic anion which contains two nitrogen
atoms. The electrogenativity of the latter two atoms also increase
the stability of the formal negative charge. Other five membered
aromatic ring anions exist, such as; cyclopentadienyl and pyrrolyl,
but these are not as stable as the imidazolate anions of this
disclosure. The cyclopentadienyl ring contains only five carbon
atoms and the pyrrolyl ring contains four carbon atoms and one
nitrogen atom. Also, the relative acidities of the ligands
cyclopentadiene, pyrrole and imidazole are 16.0, 16.45 and 14.5,
respectively, showing that imidazole is the most acidic of the
three, indicating that its conjugate base, i.e., the imidazolate
anion, is the most stable of the three. Also, the practical steric
limit for substituting large bulky groups, such as; tert-butyl onto
cyclopentadienyl, pyrrolyl and imidazolate anions is anticipated to
be three. This means that such a substituted cyclopentadienyl ring
will have two ring carbons remaining substituted with only
hydrogen, and pyrrolyl will have one ring carbon substituted with
only hydrogen. However, the analogous tri-substituted imidazolate
ring has no such ring carbons bearing only hydrogen, since all
three of its ring carbons are substituted with the three tert-butyl
type substituents.
[0066] While not wishing to be bound by theory, it is believed that
the absence of hydrogen substituents on the ring of imidazolate
anions renders them more thermally stable than either comparably
substituted cyclopenatdienyl or pyrrolly anions. Also important is
the shape and volume of the anionic ligand, because if its
structure bears large bulky groups, such as; tert-butyl, these can
ensure that the nuclearity of the resulting metal complexes will be
low, since bonding access to the ligand will be restricted to 3 or
less metal centers. The novel imidazole ligands of this disclosure
are shown to be readily functionalized with such bulky groups and
demonstrated to be capable of binding 3 or less metal centers to
make metal complexes that are volatile and highly useful as
precursors. Besides these features, it is also desirable if the
synthesis of the organic ligand can be accomplished efficiently and
in high yield and can produce pure product with no side
reactions.
[0067] It is desirable if the synthesis of the ligand permits
precise control over the introduction of different organic groups
to its structure, and this is readily achieved with the imidazole
ligands of this disclosure. Thus, if a specifically trisubstituted
imidazole ligand is targeted, it can be readily prepared in pure
form, while avoiding the formation of by products, where the
different substituents are more randomly distributed. The latter
case is more common for cyclopentadiene and pyrrole ligands,
resulting in a mixture of isomers, which need extensive separation
into their components.
[0068] It is shown that the novel imidazole ligands of this
disclosure can be synthesized in high yield and purity as only one
isomer, when asymmetrically substituted with different bulky
groups, such as; tert-butyl. This is particularly important with
respect to making a pure metal complex of lowered melting point or
a liquid, which is highly desirable, since liquid precursors are
easier to evaporate than solid precursors and are typically more
soluble in solvents to make solutions for direct liquid injection
(DLI) delivery.
[0069] To synthesize such a precursor typically entails building
ligands that are asymmetrically functionalized with steric
protecting groups, since this results in an asymmetric metal
complex, which in turn results in a lowered melting point, due to
the asymmetry lowering the crystal lattice packing energies of the
metal precursor. Thus, it is preferable that the ligand can be
efficiently asymmetrically functionalized, if desired, in a
controlled and efficient manner.
[0070] This can readily be achieved in the synthesis of the novel
imidazolate ligands of this disclosure by first synthesizing an
alpha-diketone substituted with bulky alkyl groups, which will
ultimately occupy the 4 and 5 ring positions of the imidazole ring,
then cyclizing this in the presence of ammonium acetate with an
aldheyde substituted with a bulky alkyl group, which will
ultimately occupy the 2 position of the imidazole ring. In this way
the ultimate substitution pattern of the imidazole, including
asymmetric alkylation, is readily controlled.
[0071] An example of asymmetric alkylation is found in the
comparison of FIGS. 6 and 8, which show the strontium complexes of
the tri-substituted imidazoles: 2,4,5-tri-tert-butylimidazole and
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole respectively. The
former imidazole is symmetrically substituted with three tert-butyl
groups, whereas the latter imidazole is substituted with one
tert-butyl group in the 2 position and two tert-amyl groups in the
positions 4 and 5 and is thus asymmetric.
[0072] FIGS. 7 and 9 show the thermogravimetric analysis (TGA)
results for the structures of FIGS. 6 and 8, respectively, where
the complex of FIG. 6 is shown to melt at 148.degree. C., whereas
the melting point of the structure of FIG. 8 is only 103.degree.
C.
[0073] The barium complexes of these two imidazoles, shown in FIGS.
4 and 10, show a more dramatic lowering of melting point from
151.degree. C. (shown in FIG. 5) to 65.degree. C. (shown in FIG.
11), respectively.
[0074] Thus, the effect of asymmetric tri-substitution upon
imidazole yields metal complexes of lowered melting point. It is
further anticipated that even lower melting points can be achieved,
when each of the three substituents is unique. Additionally, larger
asymmetric alkyl groups can also be used to lower the final
precursor melting point.
[0075] The novel compounds of the present invention comprise
anionic functionalized imidazolate ligands, which may be
coordinated to barium or strontium or magnesium, radium or calcium
ions to yield either monomeric or dimeric compounds, in addition to
neutral ligand adducts of those compounds, which have exceptional
thermal stability and clean evaporation characteristics.
[0076] These new complexes are also demonstrated to deliver
exceptional ALD performance with growth rates of metal oxides >2
Angstroms per cycle thereby permitting the growth of one monolayer
of metal oxide per ALD cycle. Additionally, the ALD metal oxides
grown from these new precursors are crystalline as deposited.
Typically ALD metal oxide films are not crystalline as deposited
and hence do not exhibit their full permittivity value. Hence they
need to be thermally annealed at higher than deposition
temperatures for crystallization to occur. This requires additional
processing time and subjects the device upon which the film is
grown to excessive heating which can potentially deteriorate it
performance. Therefore, being able to deliver crystalline oxide
films as deposited represents a significant manufacturing
advantage. Experimentally we find that after about 10-16 seconds of
precursor pulse, sufficient strontium is delivered to achieve a
monolayer of SrO after oxidation. Thus, good control over the
effective saturation of the initially adsorbed layers can be
achieved quickly, as shown in FIG. 19. Thus, the imidazolate metal
complexes of this disclosure are unique in their ability to grow
metal oxides at exceptionally high ALD deposition rates when
contasted to comparable cyclopentadienyl or pyrrolyl metal
precursors. TEM analysis of an ALD SrO film grown at 375.degree. C.
using di-strontium tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)
and ozone reagent, as shown in FIG. 20, clearly indicates a regular
array of metal oxide atoms which are spaced at 24 grains per 6.6
nm=66/24=2.75 Angstroms which corresponds precisely with the unit
cell dimensions of pure (001) strontium oxide. In addition, if the
amorphous layer below this array were annealed into a crystalline
phase it should yield about 23 layer to give a total of 24+23=47
layers of SrO. Experimentally, 50 ALD cycles were used so this
confirms the effective deposition of .about.1 monolayer of
SrO/cycle.
[0077] The imidazolate rings can also be asymmetrically substituted
to yield lower melting point compounds of high solubility, well
suited to direct liquid injection (DLI). The structure of the
ligand 2,5-di-tertbutylimidazole, an imidazole ligand created
according to this disclosure, Example 1, is shown in FIG. 1.
[0078] The present invention is, in one embodiment, an imidazole
substituted in at least the 2,5-positions with a bulky group, R, of
the formula:
##STR00002##
[0079] Wherein R.sup.1 and R.sup.3 are individually bulky groups
having sufficient 3-dimensional form to impart a property to the
imidazole so that after it is deprotonated to give imidazolate
anion it can bond with metals in a eta-5 bond, eta-4, eta-3, eta-2
or eta-1 bond; and R.sub.2 can be a bulky group or a group which is
not a bulky group. R.sup.1, R.sup.2 and R.sup.3 can also be bulky
groups which contain an unsaturation such as a carbon-carbon double
bond or a carbon-carbon triple bond.
[0080] Preferably, the imidazole is: [0081]
2,4,5-tri-tert-butylimidazole [0082]
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole [0083]
2-tert-butyl-4,5-di-(1,1-dimethylbutyl)imidazole [0084]
2-tert-butyl-4,5-di-(1,1-dimethylpentyl)imidazole [0085]
2-tert-butyl-4,5-di-(1,1-dimethylhexyl)imidazole [0086]
2-(1,1-dimethylpropyl)-4,5-di-tert-butylimidazole [0087]
2,4,5-tri-(1,1-dimethylpropyl)imidazole [0088]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0089]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0090]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0091]
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole [0092]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl) [0093]
2,4,5-tri-(1,1-dimethylbutyl)imidazole [0094]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0095]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0096]
2-(1,1-dimethylpentyl)-4,5-di-tert-butylimidazole [0097]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0098]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0099]
2,4,5-tri-(1,1-dimethylpentyl)imidazole [0100]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0101]
2-(1,1-dimethylhexyl)-4,5-di-tert-butylimidazole [0102]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0103]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0104]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0105]
2,4,5-tri-(1,1-dimethylhexyl)imidazole [0106]
2,4-di-tert-butyl-5-(1,1-dimethylpropyl)imidazole [0107]
2,5-di-tert-butyl-4-(1,1-dimethylpropyl)imidazole [0108]
2,4-di-tert-butyl-5-(1,1-dimethylbutyl)imidazole [0109]
2,5-di-tert-butyl-4-(1,1-dimethylbutyl)imidazole [0110]
2,4-di-tert-butyl-5-(1,1-dimethylpentyl)imidazole [0111]
2,5-di-tert-butyl-4-(1,1-dimethylpentyl)imidazole [0112]
2,4-di-tert-butyl-5-(1,1-dimethylhexyl)imidazole [0113]
2,5-di-tert-butyl-4-(1,1-dimethylhexyl)imidazole [0114]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole
[0115]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidazole
[0116]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole
[0117]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)imidazol-
e [0118]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazol-
e [0119]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)imidazol-
e [0120]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidazol-
e [0121]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)imidazol-
e [0122]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazol-
e [0123]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)imidazol-
e [0124]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazo-
le [0125] 2-(1,1-dimethylpropyl)-4-(1,1-dim
ethylpropyl)-5-tert-butyl-imidazole [0126]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0127]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-tert-butyl-imidazole
[0128]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazol-
e [0129]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-tert-butyl-imidaz-
ole [0130]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidaz-
ole [0131] 2-(1,1-dimethylpropyl)-4-(1,1-dim
ethylhexyl)-5-tert-butyl-imidazole [0132]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole [0133]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)imidazole [0134]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole [0135]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)imidazole [0136]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazole [0137]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)imidazole [0138]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidaz-
ole [0139]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpen-
tyl)imidazole [0140]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0141]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpen-
tyl)imidazole [0142]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0143]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylbutyl)-5-tert-butyl-imidazole
[0144] 2,4-di(1,1-dimethylbutyl)-5-tert-butyl-imidazole [0145]
2,5-di(1,1-dimethylbutyl)-4-tert-butyl-imidazole [0146]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[0147] 2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-tert-butyl
imidazole [0148]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0149]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidazole
[0150] 2,4-di(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidazole
[0151] 2,5-di(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)imidazole
[0152]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidaz-
ole [0153]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylpro-
pyl)imidazole [0154]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazo-
le [0155]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpropy-
l)imidazole [0156]
2,4-(1,1-dimethylbutyl)-5-(1,1-dimethylbutyl)imidazole [0157]
2,5-(1,1-dimethylbutyl)-4-(1,1-dimethylbutyl)imidazole [0158]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazo-
le [0159]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpenty-
l)imidazole [0160]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0161]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazol-
e [0162]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazol-
e [0163]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-tert-butylimidazol-
e [0164]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazo-
le [0165]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpentyl)-5-tert-butylimidaz-
ole [0166]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidaz-
ole [0167]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidaz-
ole [0168]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylbu-
tyl)imidazole [0169]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidaz-
ole [0170]
2,4-di-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)imidazole [0171]
2,5-di-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)imidazole [0172]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0173]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpro-
pyl)imidazole [0174]
2,4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidazole [0175]
2,5-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)imidazole [0176]
2,4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazole [0177]
2,5-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)imidazole [0178]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0179]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazole
[0180] 2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl
butyl)imidazole [0181] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-tert-butylimidazole [0182]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl pentyl)imidazole
[0183] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
pentyl)-5-tert-butylimidazole [0184]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl hexyl)imidazole
[0185] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
hexyl)-5-tert-butylimidazole [0186]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethyl
butyl)imidazole [0187] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-(1,1-dimethylpropyl)imidazole [0188]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethyl
pentyl)imidazole [0189] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
pentyl)-5-(1,1-dimethylpropyl)imidazole [0190]
2,4-di(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)imidazole [0191]
2,5-di(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)imidazole [0192]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethyl
butyl)imidazole [0193] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-(1,1-dimethylpentyl)imidazole [0194]
2,4-di(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)imidazole [0195]
2,5-di(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)imidazole [0196]
2-(1-methylethyl)-4,5-di-tert-butylimidazole [0197]
2-(1-methylethyl)-4,5-di(1,1-dimethylpropyl)imidazole [0198]
2-(1-methylethyl)-4,5-di(1,1-dimethylbutyl)imidazole [0199]
2-(1-methylethyl)-4,5-di(1,1-dimethylpentyl)imidazole [0200]
2-(1-methylethyl)-4,5-di(1,1-dimethylhexyl)imidazole [0201]
2,4,5-tri(1-methylethyl)imidazole [0202]
2-(1-methylethyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0203]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazole
[0204]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-tert-butylimidazole
[0205]
2-(1-methylethyl)-4-tert-butylimidazole-5-(1,1-dimethylbutyl)imidazole
[0206]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-tert-butylimidazole
[0207]
2-(1-methylethyl)-4-tert-butylimidazole-5-(1,1-dimethylpentyl)imid-
azole [0208]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidazole
[0209]
2-(1-methylethyl)-4-tert-butylimidazole-5-(1,1-dimethylhexyl)imida-
zole [0210]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidazole
[0211]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)imid-
azole [0212]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)-imidazole
[0213]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imi-
dazole [0214]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)-imidazole
[0215]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imid-
azole [0216]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)-imidazole
[0217]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)-imi-
dazole [0218]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)-imidazole
[0219]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)-imi-
dazole [0220]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)-imidazole
[0221] 2,4-di-tert-butyl-5-(1-methylethyl)imidazole [0222]
2,5-di-tert-butyl-4-(1-methylethyl)imidazole [0223]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1-methylethyl)imidazole
[0224]
2-tert-butyl-4-(1-methylethyl)-5-(1,1-dimethylbutyl)imidazole
[0225]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imidazole
[0226]
2-tert-butyl-4-(1-methylethyl)-5-(1,1-dimethylpentyl)imidazole
[0227]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imidazole
[0228]
2-tert-butyl-4-(1-methylethyl)-5-(1,1-dimethylhexyl)imidazole
[0229]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imidazole
[0230]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0231]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-tert-butylimidazole
[0232]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0233] 2,4-di(1,1-dimethylpropyl)-5-(1-methylethyl)-imidazole
[0234] 2,5-di(1,1-dimethylpropyl)-4-(1-methylethyl)-imidazole
[0235]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylbutyl)imidazo-
le [0236]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylethy-
l)imidazole [0237]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylpentyl)imidaz-
ole [0238]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylet-
hyl)imidazole [0239]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylhexyl)imidazo-
le [0240]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylethy-
l)imidazole [0241]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0242]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-tert-butyl-5-imidazole
[0243]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1,1-dimethylpropyl)imidazole
[0244]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methylethyl)imid-
azole [0245]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1,1-dimethylbutyl)imidazole
[0246]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imida-
zole [0247]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1,1-dimethylpentyl)imidazole
[0248]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imid-
azole [0249]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1,1-dimethylhexyl)imidazole
[0250]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imida-
zole [0251]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)-5-tert-butylimidazole
[0252]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylethyl)imidazole
[0253]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)-5-tert-butylimidazole
[0254]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylethyl)imidaz-
ole [0255]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylpro-
pyl)-5-imidazole [0256]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylethyl)imidazo-
le [0257]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylbuty-
l)-5-imidazole [0258]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylethyl)imidazo-
le [0259] 2,4-di(1,1-dimethylpentyl)-5-(1,1-dimethylethyl)imidazole
[0260] 2,5-di(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)imidazole
[0261]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylhexyl)-5-imid-
azole [0262]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylethyl)imidazo-
le [0263]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethylethyl)imidazol- e
[0264]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylethyl)-5-tert-butylimidazole
[0265]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylethyl)-
imidazole [0266]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylethyl)-5-(1,1-dimethylpropyl)imidazo-
le [0267]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imi-
dazole [0268]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1,1-dimethylbutyl)-5
imidazole [0269]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imid-
azole [0270]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1,1-dimethylpentyl)imidazole
[0271] 2,4-di(1,1-dimethylhexyl)-5-(1-methylethyl)imidazole [0272]
2,5-di(1,1-dimethylhexyl)-4-(1-methylethyl)imidazole [0273]
2,4-(1-methylethyl)-5-tert-butylimidazole [0274]
2,5-(1-methylethyl)-4-tert-butylimidazole [0275]
2,4-(1-methylethyl)-5-(1,1-dimethylpropyl)imidazole [0276]
2,5-(1-methylethyl)-4-(1,1-dimethylpropyl)imidazole [0277]
2,4-(1-methylethyl)-5-(1,1-dimethylbutyl)imidazole [0278]
2,5-(1-methylethyl)-4-(1,1-dimethylbutyl)imidazole [0279]
2,4-(1-methylethyl)-5-(1,1-dimethylpentyl)imidazole [0280]
2,5-(1-methylethyl)-4-(1,1-dimethylpentyl)imidazole [0281]
2,4-(1-methylethyl)-5-(1,1-dimethylhexyl)imidazole [0282]
2,5-(1-methylethyl)-4-(1,1-dimethylhexyl)imidazole [0283]
2-(1,2-dimethylpropyl)-4,5-di-tert-butylimidazole [0284]
2-(1,2-dimethylpropyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0285]
2-(1,2-dimethylpropyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0286]
2-(1,2-dimethylpropyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0287]
2-(1,2-dimethylpropyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0288]
2-(1,2-dimethylpropyl)-4,5-di-(1-methylethyl)imidazole [0289]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0290]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazol-
e [0291]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazol-
e [0292]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-tert-butylimidazol-
e [0293]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazo-
le
[0294]
2-(1,2-dimethylpropyl)-4-(1,1-dimethypentyl)-5-tert-butylimidazole
[0295]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethyhexyl)imidazole
[0296]
2-(1,2-dimethylpropyl)-4-(1,1-dimethyhexyl)-5-tert-butylimidazole
[0297] 2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1,1-dim
ethylbutyl)imidazole [0298] 2-(1,2-dimethylpropyl)-4-(1,1-dim
ethylbutyl)-5-(1,1-dimethylpropyl)imidazole [0299]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethypentyl)imidaz-
ole [0300]
2-(1,2-dimethylpropyl)-4-(1,1-dimethypentyl)-5-(1,1-dimethylpro-
pyl)imidazole [0301]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1,1-dim
ethyhexyl)imidazole [0302]
2-(1,2-dimethylpropyl)-4-(1,1-dimethyhexyl)-5-(1,1-dimethylpropyl)imidazo-
le [0303]
2-(1,2-dimethylpropyl)-4-(1,1-dimethypentyl)-5-(1,1-dimethylbuty-
l)imidazole [0304]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethypentyl)imidazo-
le [0305]
2-(1,2-dimethylpropyl)-4-(1,1-dimethyhexyl)-5-(1,1-dimethylbutyl-
)imidazole [0306]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethyhexyl)imidazol-
e [0307]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0308]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-tert-butylimidazole
[0309]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0310]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1,1-dimethylpropyl)imi-
dazole [0311]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-(1-methylethyl)imidazole
[0312]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1,1-dimethylbutyl)imid-
azole [0313]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-(1-methylethyl)imidazole
[0314]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1,1-dimethylpentyl)imi-
dazole [0315]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imidazole
[0316]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1,1-dimethylhexyl)imid-
azole [0317]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imidazole
[0318] 2,4-di-tert-butyl-5-(1,2-dimethylpropyl)imidazole [0319]
2,5-di-tert-butyl-4-(1,2-dimethylpropyl)imidazole [0320]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpropyl)imidazole
[0321]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)imidazol-
e [0322]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imidazol-
e [0323]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazol-
e [0324]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imidazo-
le [0325]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)imidaz-
ole [0326]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0327]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0328]
2-tert-butyl-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole
[0329]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1-methylethyl)imidazole
[0330]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazol-
e [0331] 2-(1,1-dimethylpropyl)-4-(1,2-dim
ethylpropyl)-5-tert-butylimidazole [0332]
2,4-(1,1-dimethylpropyl)-5-(1,2-dimethylpropyl)imidazole [0333]
2,5-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)imidazole [0334]
2-(1,1-dimethylpropyl)-4-(1,2-dim ethylpropyl)-5-(1,1-dim
ethylbutyl)imidazole [0335]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0336] 2-(1,1-dimethylpropyl)-4-(1,2-dim
ethylpropyl)-5-(1,1-dim ethylpentyl)imidazole [0337]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imida-
zole [0338] 2-(1,1-dimethylpropyl)-4-(1,2-dim
ethylpropyl)-5-(1,1-dimethylhexyl)imidazole [0339]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0340] 2-(1,1-dimethylpropyl)-4-(1,2-dim
ethylpropyl)-5-(1-methylethyl)imidazole [0341]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole
[0342]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazol-
e [0343]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-tert-butylimidazol-
e [0344] 2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,2-dim
ethylpropyl)-5-imidazole [0345]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)imidaz-
ole [0346]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpro-
pyl)imidazole [0347]
2,4-di(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imidazole [0348]
2,5-di(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)imidazole [0349]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0350]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpen-
tyl)-5-imidazole [0351]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidazo-
le [0352]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylhexy-
l)-5-imidazole [0353]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole
[0354]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1-methylethyl)-5-i-
midazole [0355]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0356]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-tert-butylimidazol-
e [0357]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylprop-
yl)imidazole [0358]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5(-1,2-dimethylpropyl)-5imi-
dazole [0359]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)imidaz-
ole [0360]
2,4-di(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl))imidazole [0361]
2,5-di(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl))imidazole [0362]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0363]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylhe-
xyl)imidazole [0364]
2-(1,1-dimethylpentyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole
[0365]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1-methylethyl)imi-
dazole [0366]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-tert-butylimidazole
[0367]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0368]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)imidaz-
ole [0369]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpro-
pyl)imidazole [0370]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazo-
le [0371]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropy-
l)imidazole [0372]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)imidaz-
ole [0373]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpro-
pyl)imidazole [0374]
2,4-di(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidazole [0375]
2,5-di(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)imidazole [0376]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1-methylethyl)imidazole
[0377]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imid-
azole [0378]
2-(1-methylethyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0379]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-tert-butyl-imidazole
[0380]
2-(1-methylethyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0381]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)imidazole
[0382]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpropyl)imi-
dazole [0383]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole
[0384]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imid-
azole [0385]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole
[0386]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imi-
dazole [0387]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazole
[0388] 2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1,2-dim
ethylpropyl)imidazole [0389]
2,4-di(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole [0390]
2,5-di(1-methylethyl)-4-(1,2-dimethylpropyl)imidazole [0391]
2,4-di(1,2-dimethylpropyl)-5-tert-butylimidazole [0392]
2,5-di(1,2-dimethylpropyl)-4-tert-butylimidazole [0393]
2,4-di(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)imidazole [0394]
2,5-di(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)imidazole [0395]
2,4-di(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole [0396]
2,5-di(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)imidazole [0397]
2,4-di(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole [0398]
2,5-di(1,2-dimethylpropyl)-4-(1,1-dimethylpentyl)imidazole [0399]
2,4-di(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazole [0400]
2,5-di(1,2-dimethylpropyl)-4-(1,1-dimethylhexyl)imidazole [0401]
2,4-di(1,2-dimethylpropyl)-5-(1-methylethyl)imidazole [0402]
2,5-di(1,2-dimethylpropyl)-4-(1-methylethyl)imidazole
[0403] Preferably the imidazole is [0404]
2,4,5-tri-tert-butylimidazole [0405]
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole [0406]
2-tert-butyl-4,5-di-(1,1-dimethylbutyl)imidazole [0407]
2-tert-butyl-4,5-di-(1,1-dimethylpentyl)imidazole [0408]
2-tert-butyl-4,5-di-(1,1-dimethylhexyl)imidazole [0409]
2-(1,1-dimethylpropyl)-4,5-di-tert-butylimidazole [0410]
2,4,5-tri-(1,1-dimethylpropyl)imidazole [0411]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0412]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0413]
2-(1,1-dimethylpropyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0414]
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole [0415]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl) [0416]
2,4,5-tri-(1,1-dimethylbutyl)imidazole [0417]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0418]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0419]
2-(1,1-dimethylpentyl)-4,5-di-tert-butylimidazole [0420]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0421]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0422]
2,4,5-tri-(1,1-dimethylpentyl)imidazole [0423]
2-(1,1-dimethylpentyl)-4,5-di-(1,1-dimethylhexyl)imidazole [0424]
2-(1,1-dimethylhexyl)-4,5-di-tert-butylimidazole [0425]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0426]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylbutyl)imidazole [0427]
2-(1,1-dimethylhexyl)-4,5-di-(1,1-dimethylpentyl)imidazole [0428]
2,4,5-tri-(1,1-dim ethylhexyl)imidazole [0429]
2,4-di-tert-butyl-5-(1,1-dimethylpropyl)imidazole [0430]
2,5-di-tert-butyl-4-(1,1-dimethylpropyl)imidazole [0431]
2,4-di-tert-butyl-5-(1,1-dimethylbutyl)imidazole [0432]
2,5-di-tert-butyl-4-(1,1-dimethylbutyl)imidazole [0433]
2,4-di-tert-butyl-5-(1,1-dimethylpentyl)imidazole [0434]
2,5-di-tert-butyl-4-(1,1-dimethylpentyl)imidazole [0435]
2,4-di-tert-butyl-5-(1,1-dimethylhexyl)imidazole [0436]
2,5-di-tert-butyl-4-(1,1-dimethylhexyl)imidazole [0437]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole
[0438]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidazole
[0439]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole
[0440]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)imidazol-
e [0441]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazol-
e [0442]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)imidazol-
e [0443]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidazol-
e [0444]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)imidazol-
e [0445]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazol-
e [0446]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)imidazol-
e [0447]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazo-
le [0448]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-tert-butyl-imida-
zole [0449]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0450] 2-(1,1-dimethylpropyl)-4-(1,1-dim
ethylbutyl)-5-tert-butyl-imidazole [0451]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazol-
e [0452] 2-(1,1-dimethylpropyl)-4-(1,1-dim
ethylpentyl)-5-tert-butyl-imidazole [0453]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0454] 2-(1,1-dimethylpropyl)-4-(1,1-dim
ethylhexyl)-5-tert-butyl-imidazole [0455]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)imidazole [0456]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)imidazole [0457]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidazole [0458]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)imidazole [0459]
2,4-di-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazole [0460]
2,5-di-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)imidazole [0461]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidaz-
ole [0462]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpen-
tyl)imidazole [0463]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0464]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpen-
tyl)imidazole [0465]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0466]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylbutyl)-5-tert-butyl-imidazole
[0467] 2,4-di(1,1-dimethylbutyl)-5-tert-butyl-imidazole [0468]
2,5-di(1,1-dimethylbutyl)-4-tert-butyl-imidazole [0469]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[0470] 2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-tert-butyl
imidazole [0471]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0472]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidazole
[0473] 2,4-di(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidazole
[0474] 2,5-di(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)imidazole
[0475]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)imidaz-
ole [0476]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylpro-
pyl)imidazole [0477]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidazo-
le [0478]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpropy-
l)imidazole [0479]
2,4-(1,1-dimethylbutyl)-5-(1,1-dimethylbutyl)imidazole [0480]
2,5-(1,1-dimethylbutyl)-4-(1,1-dimethylbutyl)imidazole [0481]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazo-
le [0482]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpenty-
l)imidazole [0483]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0484]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazol-
e [0485]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazol-
e [0486]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-tert-butylimidazol-
e [0487]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazo-
le [0488]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpentyl)-5-tert-butylimidaz-
ole [0489]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidaz-
ole [0490]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-tert-butylimidaz-
ole [0491]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylbu-
tyl)imidazole [0492]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)imidaz-
ole [0493]
2,4-di-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)imidazole [0494]
2,5-di-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)imidazole [0495]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0496]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1,1-dimethylpro-
pyl)imidazole [0497]
2,4-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)imidazole [0498]
2,5-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)imidazole [0499]
2,4-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)imidazole [0500]
2,5-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)imidazole [0501]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0502]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-tert-butylimidazole
[0503] 2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl
butyl)imidazole [0504] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-tert-butylimidazole [0505]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl pentyl)imidazole
[0506] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
pentyl)-5-tert-butylimidazole [0507]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1,1-dimethyl hexyl)imidazole
[0508] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
hexyl)-5-tert-butylimidazole [0509]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethyl
butyl)imidazole [0510] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-(1,1-dimethylpropyl)imidazole [0511]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1,1-dimethyl
pentyl)imidazole [0512] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
pentyl)-5-(1,1-dimethylpropyl)imidazole [0513]
2,4-di(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)imidazole [0514]
2,5-di(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)imidazole [0515]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1,1-dimethyl
butyl)imidazole [0516] 2-(1,1-dimethylhexyl)-4-(1,1-dimethyl
butyl)-5-(1,1-dimethylpentyl)imidazole [0517]
2,4-di(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)imidazole [0518]
2,5-di(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)imidazole
[0519] Preferably the imidazole is [0520]
2,4,5-tri-tert-butylimidazole [0521]
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole [0522]
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole [0523]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole [0524]
2-tertbutyl-4,5-di(1-methyl-1-ethylpropyl)imidazole [0525]
2-(1,1-dimethylpropyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0526]
2-(1,1-dimethylbutyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0527]
2-(1,1-dimethylpentyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0528]
2-(1,1-dimethylhexyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0529]
2-(1,1-dimethylhexyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0530] 2-(1-methylethyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[0531] 2,4,5-tri(1-methyl-1-ethylpropyl)imidazole [0532]
2,4-di-ter-butyl-5-(1-methyl-1-ethylpropyl)imidazole [0533]
2,5-di-ter-butyl-4-(1-methyl-1-ethylpropyl)imidazole [0534]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0535]
2-tert-butyl-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)imid-
azole [0536]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0537]
2-tert-butyl-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imida-
zole [0538]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0539]
2-tert-butyl-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)imid-
azole [0540]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0541]
2-tert-butyl-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imida-
zole [0542]
2-tert-butyl-4-(1-methylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0543]
2-tert-butyl-5-(1-methylpropyl)-4-(1-methyl-1-ethylpropyl)imidazol-
e [0544]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imi-
dazole [0545]
2-tert-butyl-5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)imidazole
[0546]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imid-
azole [0547]
2-(1,1-dimethylpropyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imidazole
[0548] 2,4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0549]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpr-
opyl)imidazole [0550]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0551]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0552]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0553]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0554]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0555]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0556]
2-(1,1-dimethylpropyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0557]
2-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0558]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0559]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[0560]
2-(1,1-dimethylbutyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imida-
zole [0561]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0562]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0563]
2,4-di(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0564]
2,5-di(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imidazole
[0565]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0566]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0567]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imi-
dazole [0568]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imi-
dazole [0569]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidazo-
le [0570]
2-(1,1-dimethylbutyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpropy-
l)imidazole [0571]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0572]
2-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0573]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[0574]
2-(1,1-dimethylpentyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imid-
azole [0575]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0576]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0577]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0578]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0579]
2-4-di(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)imidazole
[0580]
2-5-di(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)imidazole
[0581]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0582]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0583]
2-(1,1-dimethylpentyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0584]
2-(1,1-dimethylpentyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0585]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0586]
2-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0587]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[0588]
2-(1,1-dimethylhexyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imida-
zole [0589]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0590]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0591]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imi-
dazole [0592]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imi-
dazole [0593]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0594]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0595]
2,4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imidazole [0596]
2,5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imidazole [0597]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidazo-
le [0598]
2-(1,1-dimethylhexyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpropy-
l)imidazole [0599]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0600]
2-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0601]
2-(1-methylethyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[0602]
2-(1-methylethyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imidazole
[0603]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0604]
2-(1-methylethyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0605]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imidazo-
le [0606]
2-(1-methylethyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropy-
l)imidazole [0607]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0608]
2-(1-methylethyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0609]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imidazo-
le [0610]
2-(1-methylethyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropy-
l)imidazole [0611]
2,4-di(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidazole [0612]
2,5-di(1-methylethyl)-4-(1-methyl-1-ethylpropyl)imidazole [0613]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0614]
2-(1-methylethyl)-5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0615]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[0616]
2-(1,2-dimethylpropyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imid-
azole [0617]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0618]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0619]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0620]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0621]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [0622]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [0623]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [0624]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [0625]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [0626]
2-(1,2-dimethylpropyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [0627]
2,4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole [0628]
2,5-(1,2-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)imidazole [0629]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0630]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylpropyl)imid-
azole [0631]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0632]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylbutyl)imida-
zole [0633]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[0634]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylpentyl)imid-
azole [0635]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0636]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylhexyl)imida-
zole [0637]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidaz-
ole [0638]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbu-
tyl)imidazole [0639]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imida-
zole [0640]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imida-
zole [0641]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imidaz-
ole [0642]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhe-
xyl)imidazole [0643]
2-(1-methyl-1-ethylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylbutyl)imidaz-
ole [0644]
2-(1-methyl-1-ethylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylbu-
tyl)imidazole [0645]
2-(1-methyl-1-ethylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylhexyl)imidaz-
ole [0646]
2-(1-methyl-1-ethylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylhe-
xyl)imidazole [0647]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0648]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1-methylethyl)imidazole
[0649]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(1-methylethyl)imidaz-
ole [0650]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylet-
hyl)imidazole [0651]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imidazo-
le [0652]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylethy-
l)imidazole [0653]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imidaz-
ole [0654]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylet-
hyl)imidazole [0655]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imidazo-
le [0656]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylethy-
l)imidazole [0657]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0658]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,2-dimethylpropyl)imid-
azole [0659]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0660] 2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(1,2-dim
ethylpropyl) imidazole [0661]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)i-
midazole [0662]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)im-
idazole [0663]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)im-
idazole [0664]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)i-
midazole [0665]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)i-
midazole [0666]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)im-
idazole [0667]
2-(1-methyl-1-ethylpropyl)-5-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)im-
idazole [0668]
2-(1-methyl-1-ethylpropyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidaz-
ole [0669]
2-(1-methyl-1-ethylpropyl)-5-(1-methylethyl)-4-(1,2-dimethylpro-
pyl)imidazole [0670]
2,4-di(1-methyl-1-ethylpropyl)-5-tert-butylimidazole [0671]
2,5-di(1-methyl-1-ethylpropyl)-4-tert-butylimidazole [0672]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpropyl)imidazole
[0673]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)imidazole
[0674]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylbutyl)imidazole
[0675]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylbutyl)imidazole
[0676]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpentyl)imidazole
[0677]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpentyl)imidazole
[0678]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylhexyl)imidazole
[0679]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylhexyl)imidazole
[0680] 2,4-di(1-methyl-1-ethylpropyl)-5-(1-methylethyl)imidazole
[0681] 2,5-di(1-methyl-1-ethylpropyl)-4-(1-methylethyl)imidazole
[0682]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,2-dimethylpropyl)imidazole
[0683]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,2-dimethylpropyl)imidazole
[0684] 2-tertbutyl-4,5-di(1-methylpropyl)imidazole [0685]
2-(1,1-dimethylpropyl)-4,5-di(1-methylpropyl)imidazole [0686]
2-(1,1-dimethylbutyl)-4,5-di(1-methylpropyl)imidazole [0687]
2-(1,1-dimethylpentyl)-4,5-di(1-methylpropyl)imidazole [0688]
2-(1,1-dimethylhexyl)-4,5-di(1-methylpropyl)imidazole [0689]
2-(1,1-dimethylhexyl)-4,5-di(1-methylpropyl)imidazole [0690]
2-(1-methylethyl)-4,5-di(1-methylpropyl)imidazole [0691]
2,4,5-tri(1-methylpropyl)imidazole [0692]
2,4-di-ter-butyl-5-(1-methylpropyl)imidazole [0693]
2,5-di-ter-butyl-4-(1-methylpropyl)imidazole [0694]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)imidazole
[0695]
2-tert-butyl-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0696]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imidazole
[0697]
2-tert-butyl-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imidazole
[0698]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)imidazole
[0699]
2-tert-butyl-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)imidazole
[0700]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidazole
[0701]
2-tert-butyl-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imidazole
[0702] 2-tert-butyl-4-(1-methylpropyl)-5-(1-methylpropyl)imidazole
[0703] 2-tert-butyl-5-(1-methylpropyl)-4-(1-methylpropyl)imidazole
[0704]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)imidazole
[0705]
2-tert-butyl-5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0706]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0707]
2-(1,1-dimethylpropyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0708] 2,4-(1,1-dimethylpropyl)-5-(1-methylpropyl)imidazole [0709]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imidazole
[0710]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imi-
dazole [0711]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)imidazole
[0712]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)im-
idazole [0713]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidazole
[0714]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imi-
dazole [0715]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-(1-methylpropyl)imidazole
[0716]
2-(1,1-dimethylpropyl)-5-(1-methylethyl)-4-(1-methylpropyl)imidazo-
le [0717]
2-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)-
imidazole [0718]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0719]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0720]
2-(1,1-dimethylbutyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0721]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)imi-
dazole [0722]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0723] 2,4-di(1,1-dimethylbutyl)-5-(1-methylpropyl)imidazole [0724]
2,5-di(1,1-dimethylbutyl)-4-(1-methylpropyl)imidazole [0725]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)imidazole
[0726]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)imi-
dazole [0727]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidazole
[0728]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imid-
azole [0729]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1-methylpropyl)imidazole
[0730]
2-(1,1-dimethylbutyl)-5-(1-methylethyl)-4-(1-methylpropyl)imidazol-
e [0731]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)im-
idazole [0732]
2-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0733]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0734]
2-(1,1-dimethylpentyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0735]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)im-
idazole [0736]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0737]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imi-
dazole [0738]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imidazole
[0739] 2-4-di(1,1-dimethylpentyl)-5-(1-methylpropyl)imidazole
[0740] 2-5-di(1,1-dimethylpentyl)-4-(1-methylpropyl)imidazole
[0741]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidazole
[0742]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imi-
dazole [0743]
2-(1,1-dimethylpentyl)-4-(1-methylethyl)-5-(1-methylpropyl)imidazole
[0744]
2-(1,1-dimethylpentyl)-5-(1-methylethyl)-4-(1-methylpropyl)imidazo-
le [0745]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)-
imidazole [0746]
2-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0747]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0748]
2-(1,1-dimethylhexyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0749]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)imi-
dazole [0750]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0751]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imid-
azole [0752]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imidazole
[0753]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)imi-
dazole [0754]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)imidazole
[0755] 2,4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidazole [0756]
2,5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imidazole [0757]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1-methylpropyl)imidazole
[0758]
2-(1,1-dimethylhexyl)-5-(1-methylethyl)-4-(1-methylpropyl)imidazol-
e [0759]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)im-
idazole [0760]
2-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0761] 2-(1-methylethyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0762] 2-(1-methylethyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0763]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)imidazole
[0764]
2-(1-methylethyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazo-
le [0765]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imidaz-
ole [0766]
2-(1-methylethyl)-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imida-
zole [0767]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)imidazole
[0768]
2-(1-methylethyl)-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)imidazo-
le [0769]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imidaz-
ole [0770]
2-(1-methylethyl)-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imida-
zole [0771] 2,4-di(1-methylethyl)-5-(1-methylpropyl)imidazole
[0772] 2,5-di(1-methylethyl)-4-(1-methylpropyl)imidazole [0773]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1-methylpropyl)imidazole
[0774]
2-(1-methylethyl)-5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazo-
le [0775]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1-methylpropyl)imidazole
[0776]
2-(1,2-dimethylpropyl)-5-tert-butyl-4-(1-methylpropyl)imidazole
[0777]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1-methylpropyl)im-
idazole [0778]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylpropyl)imidazole
[0779]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylpropyl)imi-
dazole [0780]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylpropyl)imidazole
[0781]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylpropyl)im-
idazole [0782]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylpropyl)imidazole
[0783]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylpropyl)imi-
dazole [0784]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylpropyl)imidazole
[0785]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1-methylpropyl)imidazo-
le [0786]
2-(1,2-dimethylpropyl)-5-(1-methylethyl)-4-(1-methylpropyl)imida-
zole [0787] 2,4-(1,2-dimethylpropyl)-5-(1-methylpropyl)imidazole
[0788] 2,5-(1,2-dimethylpropyl)-4-(1-methylpropyl)imidazole [0789]
2-(1-methylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0790]
2-(1-methylpropyl)-5-tert-butyl-4-(1,1-dimethylpropyl)imidazole
[0791]
2-(1-methylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0792]
2-(1-methylpropyl)-5-tert-butyl-4-(1,1-dimethylbutyl)imidazole
[0793]
2-(1-methylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[0794]
2-(1-methylpropyl)-5-tert-butyl-4-(1,1-dimethylpentyl)imidazole
[0795]
2-(1-methylpropyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0796]
2-(1-methylpropyl)-5-tert-butyl-4-(1,1-dimethylhexyl)imidazole
[0797]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidazole
[0798]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidazo-
le [0799]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imid-
azole [0800]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imidazole
[0801]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imidazo-
le [0802]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imida-
zole [0803]
2-(1-methylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylbutyl)imidazole
[0804]
2-(1-methylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylbutyl)imidazo-
le [0805]
2-(1-methylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylhexyl)imida-
zole [0806]
2-(1-methylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylhexyl)imidazole
[0807] 2-(1-methylpropyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0808] 2-(1-methylpropyl)-5-tert-butyl-4-(1-methylethyl)imidazole
[0809]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(1-methylethyl)imidazole
[0810]
2-(1-methylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylethyl)imidazo-
le [0811]
2-(1-methylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imidaz-
ole [0812]
2-(1-methylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylethyl)imida-
zole [0813]
2-(1-methylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imidazole
[0814]
2-(1-methylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylethyl)imidazo-
le [0815]
2-(1-methylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imidaz-
ole [0816]
2-(1-methylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylethyl)imida-
zole [0817]
2-(1-methylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0818]
2-(1-methylpropyl)-5-tert-butyl-4-(1,2-dimethylpropyl)imidazole
[0819]
2-(1-methylpropyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0820]
2-(1-methylpropyl)-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpropyl)imidazole
[0821] 2-(1-methylpropyl)-5-(1,1-dimethylpropyl)-4-(1,2-dim
ethylpropyl)imidazole [0822]
2-(1-methylpropyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imidazole
[0823]
2-(1-methylpropyl)-5-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)imi-
dazole [0824]
2-(1-methylpropyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imidazole
[0825]
2-(1-methylpropyl)-5-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)im-
idazole [0826]
2-(1-methylpropyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imidazole
[0827]
2-(1-methylpropyl)-5-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)imi-
dazole [0828]
2-(1-methylpropyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazole
[0829]
2-(1-methylpropyl)-5-(1-methylethyl)-4-(1,2-dimethylpropyl)imidazo-
le [0830] 2,4-di(1-methylpropyl)-5-tert-butylimidazole [0831]
2,5-di(1-methylpropyl)-4-tert-butylimidazole [0832]
2,4-di(1-methylpropyl)-5-(1,1-dimethylpropyl)imidazole [0833]
2,5-di(1-methylpropyl)-4-(1,1-dimethylpropyl)imidazole [0834]
2,4-di(1-methylpropyl)-5-(1,1-dimethylbutyl)imidazole [0835]
2,5-di(1-methylpropyl)-4-(1,1-dimethylbutyl)imidazole [0836]
2,4-di(1-methylpropyl)-5-(1,1-dimethylpentyl)imidazole [0837]
2,5-di(1-methylpropyl)-4-(1,1-dimethylpentyl)imidazole [0838]
2,4-di(1-methylpropyl)-5-(1,1-dimethylhexyl)imidazole [0839]
2,5-di(1-methylpropyl)-4-(1,1-dimethylhexyl)imidazole [0840]
2,4-di(1-methylpropyl)-5-(1-methylethyl)imidazole [0841]
2,5-di(1-methylpropyl)-4-(1-methylethyl)imidazole [0842]
2,4-di(1-methylpropyl)-5-(1,2-dimethylpropyl)imidazole [0843]
2,5-di(1-methylpropyl)-4-(1,2-dimethylpropyl)imidazole [0844]
2-tertbutyl-4,5-di(1-methylbutyl)imidazole [0845]
2-(1,1-dimethylpropyl)-4,5-di(1-methylbutyl)imidazole [0846]
2-(1,1-dimethylbutyl)-4,5-di(1-methylbutyl)imidazole [0847]
2-(1,1-dimethylpentyl)-4,5-di(1-methylbutyl)imidazole [0848]
2-(1,1-dimethylhexyl)-4,5-di(1-methylbutyl)imidazole [0849]
2-(1,1-dimethylhexyl)-4,5-di(1-methylbutyl)imidazole [0850]
2-(1-methylethyl)-4,5-di(1-methylbutyl)imidazole [0851]
2,4,5-tri(1-methylbutyl)imidazole [0852]
2,4-di-ter-butyl-5-(1-methylbutyl)imidazole [0853]
2,5-di-ter-butyl-4-(1-methylbutyl)imidazole [0854]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0855]
2-tert-butyl-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0856]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imidazole
[0857]
2-tert-butyl-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imidazole
[0858]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imidazole
[0859]
2-tert-butyl-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imidazole
[0860]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidazole
[0861]
2-tert-butyl-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imidazole
[0862] 2-tert-butyl-4-(1-methylbutyl)-5-(1-methylbutyl)imidazole
[0863] 2-tert-butyl-5-(1-methylbutyl)-4-(1-methylbutyl)imidazole
[0864]
2-tert-butyl-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0865]
2-tert-butyl-5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0866]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0867]
2-(1,1-dimethylpropyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0868] 2,4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imidazole [0869]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imidazole
[0870]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imid-
azole [0871]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imidazole
[0872]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imi-
dazole [0873]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidazole
[0874]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imid-
azole [0875]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-(1-methylbutyl)imidazole
[0876]
2-(1,1-dimethylpropyl)-5-(1-methylethyl)-4-(1-methylbutyl)imidazol-
e [0877]
2-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)im-
idazole [0878]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0879]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0880]
2-(1,1-dimethylbutyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0881]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imid-
azole [0882]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0883] 2,4-di(1,1-dimethylbutyl)-5-(1-methylbutyl)imidazole [0884]
2,5-di(1,1-dimethylbutyl)-4-(1-methylbutyl)imidazole [0885]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imidazole
[0886]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imid-
azole [0887]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidazole
[0888]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imida-
zole [0889]
2-(1,1-dimethylbutyl)-4-(1-methylethyl)-5-(1-methylbutyl)imidazole
[0890]
2-(1,1-dimethylbutyl)-5-(1-methylethyl)-4-(1-methylbutyl)imidazole
[0891]
2-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0892]
2-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imid-
azole [0893]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0894]
2-(1,1-dimethylpentyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0895]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0896]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imi-
dazole [0897]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imidazole
[0898]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imid-
azole [0899] 2-4-di(1,1-dimethylpentyl)-5-(1-methylbutyl)imidazole
[0900] 2-5-di(1,1-dimethylpentyl)-4-(1-methylbutyl)imidazole [0901]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidazole
[0902]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imid-
azole [0903]
2-(1,1-dimethylpentyl)-4-(1-methylethyl)-5-(1-methylbutyl)imidazole
[0904]
2-(1,1-dimethylpentyl)-5-(1-methylethyl)-4-(1-methylbutyl)imidazol-
e [0905]
2-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)im-
idazole [0906]
2-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0907]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0908]
2-(1,1-dimethylhexyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0909]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imid-
azole [0910]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0911]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imida-
zole [0912]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imidazole
[0913]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imid-
azole [0914]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imidazole
[0915] 2,4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidazole [0916]
2,5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imidazole [0917]
2-(1,1-dimethylhexyl)-4-(1-methylethyl)-5-(1-methylbutyl)imidazole
[0918]
2-(1,1-dimethylhexyl)-5-(1-methylethyl)-4-(1-methylbutyl)imidazole
[0919]
2-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0920]
2-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imid-
azole [0921]
2-(1-methylethyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0922] 2-(1-methylethyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0923]
2-(1-methylethyl)-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0924]
2-(1-methylethyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazol-
e [0925]
2-(1-methylethyl)-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imidazol-
e [0926]
2-(1-methylethyl)-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imidazol-
e [0927]
2-(1-methylethyl)-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imidazo-
le [0928]
2-(1-methylethyl)-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imidaz-
ole [0929]
2-(1-methylethyl)-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imidaz-
ole [0930]
2-(1-methylethyl)-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imidaz-
ole [0931] 2,4-di(1-methylethyl)-5-(1-methylbutyl)imidazole [0932]
2,5-di(1-methylethyl)-4-(1-methylbutyl)imidazole [0933]
2-(1-methylethyl)-4-(1,2-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0934]
2-(1-methylethyl)-5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imidazol-
e [0935]
2-(1,2-dimethylpropyl)-4-tert-butyl-5-(1-methylbutyl)imidazole
[0936]
2-(1,2-dimethylpropyl)-5-tert-butyl-4-(1-methylbutyl)imidazole
[0937]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpropyl)-5-(1-methylbutyl)imi-
dazole [0938]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methylbutyl)imidazole
[0939]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methylbutyl)imid-
azole [0940]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methylbutyl)imidazole
[0941]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methylbutyl)imi-
dazole [0942]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methylbutyl)imidazole
[0943]
2-(1,2-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methylbutyl)imid-
azole [0944]
2-(1,2-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methylbutyl)imidazole
[0945]
2-(1,2-dimethylpropyl)-4-(1-methylethyl)-5-(1-methylbutyl)imidazol-
e [0946]
2-(1,2-dimethylpropyl)-5-(1-methylethyl)-4-(1-methylbutyl)imidazo-
le [0947] 2,4-(1,2-dimethylpropyl)-5-(1-methylbutyl)imidazole
[0948] 2,5-(1,2-dimethylpropyl)-4-(1-methylbutyl)imidazole [0949]
2-(1-methylbutyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[0950]
2-(1-methylbutyl)-5-tert-butyl-4-(1,1-dimethylpropyl)imidazole
[0951]
2-(1-methylbutyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[0952]
2-(1-methylbutyl)-5-tert-butyl-4-(1,1-dimethylbutyl)imidazole
[0953]
2-(1-methylbutyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[0954]
2-(1-methylbutyl)-5-tert-butyl-4-(1,1-dimethylpentyl)imidazole
[0955]
2-(1-methylbutyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[0956]
2-(1-methylbutyl)-5-tert-butyl-4-(1,1-dimethylhexyl)imidazole
[0957]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidazole
[0958]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidazol-
e [0959]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imidaz-
ole [0960]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imid-
azole [0961]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imidazole
[0962]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imidazol-
e [0963]
2-(1-methylbutyl)-4-(dimethylpentyl)-5-(1,1-dimethylbutyl)imidazo-
le [0964]
2-(1-methylbutyl)-5-(dimethylpentyl)-4-(1,1-dimethylbutyl)imidaz-
ole [0965]
2-(1-methylbutyl)-4-(dimethylpentyl)-5-(1,1-dimethylhexyl)imida-
zole [0966]
2-(1-methylbutyl)-5-(dimethylpentyl)-4-(1,1-dimethylhexyl)imidazole
[0967] 2-(1-methylbutyl)-4-tert-butyl-5-(1-methylethyl)imidazole
[0968] 2-(1-methylbutyl)-5-tert-butyl-4-(1-methylethyl)imidazole
[0969]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methylethyl)imidazole
[0970]
2-(1-methylbutyl)-5-(1,1-dimethylpropyl)-4-(1-methylethyl)imidazol-
e [0971]
2-(1-methylbutyl)-4-(1,1-dimethylbutyl)-5-(1-methylethyl)imidazol-
e [0972]
2-(1-methylbutyl)-5-(1,1-dimethylbutyl)-4-(1-methylethyl)imidazol-
e [0973]
2-(1-methylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methylethyl)imidazo-
le [0974]
2-(1-methylbutyl)-5-(1,1-dimethylpentyl)-4-(1-methylethyl)imidaz-
ole [0975]
2-(1-methylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methylethyl)imidaz-
ole [0976]
2-(1-methylbutyl)-5-(1,1-dimethylhexyl)-4-(1-methylethyl)imidaz-
ole [0977]
2-(1-methylbutyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0978]
2-(1-methylbutyl)-5-tert-butyl-4-(1,2-dimethylpropyl)imidazole
[0979]
2-(1-methylbutyl)-4-tert-butyl-5-(1,2-dimethylpropyl)imidazole
[0980]
2-(1-methylbutyl)-4-(1,1-dimethylpropyl)-5-(1,2-dimethylpropyl)imi-
dazole [0981]
2-(1-methylbutyl)-5-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)imidazole
[0982]
2-(1-methylbutyl)-4-(1,1-dimethylbutyl)-5-(1,2-dimethylpropyl)imid-
azole [0983]
2-(1-methylbutyl)-5-(1,1-dimethylbutyl)-4-(1,2-dimethylpropyl)imidazole
[0984]
2-(1-methylbutyl)-4-(1,1-dimethylpentyl)-5-(1,2-dimethylpropyl)imi-
dazole [0985]
2-(1-methylbutyl)-5-(1,1-dimethylpentyl)-4-(1,2-dimethylpropyl)imidazole
[0986]
2-(1-methylbutyl)-4-(1,1-dimethylhexyl)-5-(1,2-dimethylpropyl)imid-
azole [0987]
2-(1-methylbutyl)-5-(1,1-dimethylhexyl)-4-(1,2-dimethylpropyl)imidazole
[0988]
2-(1-methylbutyl)-4-(1-methylethyl)-5-(1,2-dimethylpropyl)imidazol-
e [0989]
2-(1-methylbutyl)-5-(1-methylethyl)-4-(1,2-dimethylpropyl)imidazo-
le [0990] 2,4-di(1-methylbutyl)-5-tert-butylimidazole [0991]
2,5-di(1-methylbutyl)-4-tert-butylimidazole [0992]
2,4-di(1-methylbutyl)-5-(1,1-dimethylpropyl)imidazole [0993]
2,5-di(1-methylbutyl)-4-(1,1-dimethylpropyl)imidazole [0994]
2,4-di(1-methylbutyl)-5-(1,1-dimethylbutyl)imidazole [0995]
2,5-di(1-methylbutyl)-4-(1,1-dimethylbutyl)imidazole [0996]
2,4-di(1-methylbutyl)-5-(1,1-dimethylpentyl)imidazole [0997]
2,5-di(1-methylbutyl)-4-(1,1-dimethylpentyl)imidazole [0998]
2,4-di(1-methylbutyl)-5-(1,1-dimethylhexyl)imidazole [0999]
2,5-di(1-methylbutyl)-4-(1,1-dimethylhexyl)imidazole [1000]
2,4-di(1-methylbutyl)-5-(1-methylethyl)imidazole [1001]
2,5-di(1-methylbutyl)-4-(1-methylethyl)imidazole [1002]
2,4-di(1-methylbutyl)-5-(1,2-dimethylpropyl)imidazole [1003]
2,5-di(1-methylbutyl)-4-(1,2-dimethylpropyl)imidazole
[1004] More preferably, the imidazole is one of: [1005]
2-tertbutyl-4,5-di(1-methyl-1-ethylpropyl)imidazole [1006]
2-(1,1-dimethylpropyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1007]
2-(1,1-dimethylbutyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1008]
2-(1,1-dimethylpentyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1009]
2-(1,1-dimethylhexyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1010]
2-(1,1-dimethylhexyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1011] 2-(1-methylethyl)-4,5-di(1-methyl-1-ethylpropyl)imidazole
[1012] 2,4,5-tri(1-methyl-1-ethylpropyl)imidazole [1013]
2,4-di-ter-butyl-5-(1-methyl-1-ethylpropyl)imidazole [1014]
2,5-di-ter-butyl-4-(1-methyl-1-ethylpropyl)imidazole [1015]
2-tert-butyl-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1016]
2-tert-butyl-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)imid-
azole [1017]
2-tert-butyl-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1018]
2-tert-butyl-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imida-
zole [1019]
2-tert-butyl-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1020]
2-tert-butyl-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)imid-
azole [1021]
2-tert-butyl-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1022]
2-tert-butyl-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imida-
zole [1023]
2-(1,1-dimethylpropyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[1024]
2-(1,1-dimethylpropyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imid-
azole [1025]
2,4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)imidazole [1026]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpr-
opyl)imidazole [1027]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1028]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [1029]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [1030]
2-(1,1-dimethylpropyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1031]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1032]
2-(1,1-dimethylpropyl)-4-(1-methylethyl)-5-(1-methyl-1-ethylpropyl)imidaz-
ole [1033]
2-(1,1-dimethylpropyl)-5-(1-methylethyl)-4-(1-methyl-1-ethylpro-
pyl)imidazole [1034]
2-(1,1-dimethylpropyl)-4-(1,2-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [1035]
2-(1,1-dimethylpropyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [1036]
2-(1,1-dimethylbutyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[1037]
2-(1,1-dimethylbutyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imida-
zole [1038]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1039]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1040]
2,4-di(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1041]
2,5-di(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imidazole
[1042]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1043]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1044]
2-(1,1-dimethylbutyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imi-
dazole [1045]
2-(1,1-dimethylbutyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imi-
dazole [1046]
2-(1,1-dimethylpentyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[1047]
2-(1,1-dimethylpentyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imid-
azole [1048]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)i-
midazole [1049]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)i-
midazole [1050]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1051]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1052]
2-4-di(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)imidazole
[1053]
2-5-di(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)imidazole
[1054]
2-(1,1-dimethylpentyl)-4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1055]
2-(1,1-dimethylpentyl)-5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1056]
2-(1,1-dimethylhexyl)-4-tert-butyl-5-(1-methyl-1-ethylpropyl)imidazole
[1057]
2-(1,1-dimethylhexyl)-5-tert-butyl-4-(1-methyl-1-ethylpropyl)imida-
zole [1058]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpropyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1059]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpropyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1060]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylbutyl)-5-(1-methyl-1-ethylpropyl)imi-
dazole [1061]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylbutyl)-4-(1-methyl-1-ethylpropyl)imi-
dazole [1062]
2-(1,1-dimethylhexyl)-4-(1,1-dimethylpentyl)-5-(1-methyl-1-ethylpropyl)im-
idazole [1063]
2-(1,1-dimethylhexyl)-5-(1,1-dimethylpentyl)-4-(1-methyl-1-ethylpropyl)im-
idazole [1064]
2,4-(1,1-dimethylhexyl)-5-(1-methyl-1-ethylpropyl)imidazole [1065]
2,5-(1,1-dimethylhexyl)-4-(1-methyl-1-ethylpropyl)imidazole [1066]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylpropyl)imidazole
[1067]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylpropyl)imid-
azole [1068]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylbutyl)imidazole
[1069]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylbutyl)imida-
zole [1070]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylpentyl)imidazole
[1071]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylpentyl)imid-
azole [1072]
2-(1-methyl-1-ethylpropyl)-4-tert-butyl-5-(1,1-dimethylhexyl)imidazole
[1073]
2-(1-methyl-1-ethylpropyl)-5-tert-butyl-4-(1,1-dimethylhexyl)imida-
zole [1074]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbutyl)imidaz-
ole [1075]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylbu-
tyl)imidazole [1076]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imida-
zole [1077]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylpentyl)imida-
zole [1078]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhexyl)imidaz-
ole [1079]
2-(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)-5-(dimethylhe-
xyl)imidazole [1080]
2-(1-methyl-1-ethylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylbutyl)imidaz-
ole [1081]
2-(1-methyl-1-ethylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylbu-
tyl)imidazole [1082]
2-(1-methyl-1-ethylpropyl)-4-(dimethylpentyl)-5-(1,1-dimethylhexyl)imidaz-
ole [1083]
2-(1-methyl-1-ethylpropyl)-5-(dimethylpentyl)-4-(1,1-dimethylhe-
xyl)imidazole [1084]
2,4-di(1-methyl-1-ethylpropyl)-5-tert-butylimidazole [1085]
2,5-di(1-methyl-1-ethylpropyl)-4-tert-butylimidazole [1086]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpropyl)imidazole
[1087]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpropyl)imidazole
[1088]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylbutyl)imidazole
[1089]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylbutyl)imidazole
[1090]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylpentyl)imidazole
[1091]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylpentyl)imidazole
[1092]
2,4-di(1-methyl-1-ethylpropyl)-5-(1,1-dimethylhexyl)imidazole
[1093]
2,5-di(1-methyl-1-ethylpropyl)-4-(1,1-dimethylhexyl)imidazole
[1094] These imidazoles can then be deprotonated to yield their
respective imidazolate anions, which can then coordinate to barium,
strontium, calcium or radium ions to, in turn, yield their
respective complexes.
[1095] Preferably, the imidazolate's R.sub.1 and R.sub.3 are
individually selected from the group consisting of tert-butyl,
isopropyl, tert-amyl, neopentyl, adamantly, hexyl, cyclohexyl,
propyl, butyl, isobutyl, pentyl, cyclopentyl, isopentyl, neopenty,
norbornyl, bicyclo[2.2.1]heptyl, propyl, butyl, isobutyl, pentyl,
isopentyl, dimethylbutyl, dimethylpentyl, dimethylhexyl, sec butyl,
ethylmethylpropyl, isohexyl, isopentyl.
[1096] Preferably, the imidazolate's R.sub.2 is a bulky group
selected from the group consisting of tert-butyl, isopropyl,
tert-amyl, neopentyl, adamantly, hexyl, hexyl, cyclohexyl, propyl,
butyl, isobutyl, pentyl, cyclopentyl, isopentyl, neopenty,
norbornyl, bicyclo[2.2.1]heptyl, propyl, butyl, isobutyl, pentyl,
isopentyl, dimethylbutyl, dim ethylpentyl, dimethylhexyl, sec
butyl, ethylmethylpropyl, isohexyl, isopentyl.
[1097] Most preferably, the imidazolate is [1098]
2,4,5-tri-tert-butylimidazolate [1099]
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate [1100]
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate [1101]
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate; and
their barium, strontium, magnesium and calcium salts.
[1102] In another aspect, the present invention teaches compounds
comprising one or more polysubstituted imidazolate anions
coordinated to a metal selected from the group consisting of
barium, strontium, magnesium, calcium or radium or mixtures
thereof.
[1103] Alternatively, one imidazolate anion can be substituted with
a second non-imidazolate anion. In addition, the imidazolate anion
may also bear a substituent, which is also deprotonated to yield a
dianionic species, and this dianion is coordinated to a metal, such
as barium, strontium, magnesium, calcium or radium or mixtures
thereof.
[1104] Synthesis of the novel compounds and their use to form BST
films is also contemplated.
[1105] To understand the unique character of these ligands, it is
instructive to consider the structure and substitutional numbering
system of unsubstituted imidazole, as shown in Formula A. Note that
the ring numbering system indicates that when all three carbon
atoms of the imidazole ring are substituted with alkyl groups, then
the resulting molecule would be called a
2,4,5-trialkylimidazole.
##STR00003##
[1106] When the N--H group of imidazole is deprotonated at position
1, the resulting formal negative charge of the anion thus created
is delocalized throughout the five membered ring. However, if such
an anion coordinates to metal cations it will typically do so
through both of the nitrogen atoms, not involving the three carbon
atoms of the ring. In this way, the imidazole anion most typically
behaves as a linear `bridging anion` between metal centers.
[1107] This very strong tendency for imidazolates to linearly
bridge metal cations is frequently utilized as a technique to build
framework complexes, where the imidazole act as a molecular
scaffold to link metals cations together, as illustrated in Formula
B. Being highly associated, such structures are involatile.
##STR00004##
PRIOR ART
[1108] The novel imidazole ligands of the present invention are
unique in that they are substituted in at least the 2 and 5
positions, more preferably the 2,4 and 5 positions on the imidazole
ring using sufficiently bulky groups such as tert-butyl, that when
the imidazole is deprotonated to give an imidazolate anion, it does
not coordinate to a metal to form a highly associated structure as
in Formula B, but rather other modes of coordination to the metal
become possible. One possible mode of coordination then becomes an
`eta-5` mode, where the plane of the five membered ring is
positioned sideways to the metal ion. This then permits the metal
to bond to all five atoms of the imidazolate ring, as shown in
Formula C, where R represents bulky alkyl type groups.
[1109] Bulky groups for the purpose of the present invention are
groups which have sufficient 3-dimensional spacial form to create
the steric hindrance needed so that metals bonding with the
imidazolates of the present invention are enabled to be preferably
bonded in the `eta-5` bonding or `end on` eta-1' bonding of
Formulae C and D respectively. Additionally, the bonding modes
between these two extremes are also possible, such as: eta-2, eta-3
and eta-4.
##STR00005##
[1110] More preferably, bulky groups for the purpose of the present
invention are groups which have sufficient 3-dimensional spacial
form to create sufficient steric hindrance so that metals bonding
with the imidazolates of the present invention are enabled to be
bonded in the `eta-5` bonding of Formula D.
##STR00006##
[1111] The structure depicted in Formula D represents an unexpected
result in that the vast preponderance of imidazole anions (ie
imidazolates) do not bind in an `eta-5` or sideways manner, but
rather linearly only though the nitrogen atoms, as in Formula
B.
[1112] In the Cambridge crystallographic data base there is only
one example of an eta-5 metal-to-imidazolate ion coordination (M.
Tadokoro, T. Shiomi, K. Isob, K. Nakasuji, Inorganic Chem. 40
5476-5478 (2001)), and it occurs in an involatile mixed metal
polymeric coordination compound, rather than in the discreet and
volatile metal complexes of the present invention, further
underscoring the unique character of the present invention's novel
imidazole ligands.
[1113] Additionally, the imidazolate anions of this disclosure can
also bond in a novel `end on` manner as shown in Formula C where
the bulky substituents permit the metal to bond only to to one of
the imidazolate nitrogens. This is illustrated in FIG. 8 where the
two terminal imidazolate anions of di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl)imidazolate) are seen
to bind to strontium by only one nitrogen. While not wishing to be
bound by theory, it is also anticipated that other novel bonding
modes exist between the two extremes of eta-5 and eta-1, where only
two, three or four of the imidazolate ring atoms participate in
bonding to the metal.
[1114] Bulky groups can comprise C.sub.3-12 groups, preferably
branched alkyl, cyclic or aromatic, and optionally further
derivatized with other functional groups such as amine, alkoxy,
hydroxyl, carboxylic, substituted amine and similar derivatives.
Alkanes, alkenes, alkynes, cyclic forms of the same, aromatics, and
their derivatives are all contemplated as bulky groups, as long as
they meet the requirement of having sufficient bulk in the form of
3-dimensional spacial form to induce eta-4, eta-3, to 2 or eta-1,
and more preferably `eta-5` bonding of the imidazole with metals.
Other suitable bulky alkyl groups include, but are not limited to,
isopropyl, tert-amyl, neopentyl, adamantly, hexyl, cyclohexyl,
propyl, butyl, isobutyl, tertbutyl, pentyl, isopentyl, neopenty,
norbornyl, bicyclo[2.2.1]heptyl, C.sub.9-C.sub.20 alkylphenyl,
C.sub.1-C.sub.10 alkoxy; C.sub.1-C.sub.10 alkylamine;
C.sub.1-C.sub.10 alkyl functionalized with a heteroatom substituted
ring structure selected from the group consisting of imidazole,
pyrrole, pyridine, furan, pyrimidine, pyrazole; C.sub.1-C.sub.10
alkyl functionalized with an amide group; C.sub.1-C.sub.10 alkyl
functionalized with an ester group and mixtures thereof.
[1115] As can be seen in FIGS. 4, 6, 10, 13 and 15, the bulky
groups can induce `eta-5` bonding, as exemplified by the terminal
imidazolate anions present in these structures. However, the
central imidazolates act as `bridging` anions connecting the two
metal centers together, where the axis of the metal-nitrogen bonds
are not in the plane of the imidazolate ring, but rather both
pointed to one side of the plane. Not wishing to be bound by any
theory, it is believed that the bulky groups induce a preference
for, eta-4, eta-3, eta-2 or eta-1, and more preferably eta-5
bonding, and when such bonding is satisfied, additional linear
non-planar bonding is also permitted by the bulky groups, possibly
due to steric hindrance effects after two bulky group substituted
imidazoles are bound to the metal. Thus, in the present invention,
when the bulky groups are characterized by stating they impart a
property to the imidazolate to bond with metals in an, eta-4,
eta-3, eta-2 or eta-1, and more preferably `eta-5 bond`, this does
not preclude additional bonding in linear fashion in addition to
`eta-5` etc, but merely describes a favored or preferred bonding
form. Without the bulky groups, these imidazolates would not
exhibit the property to favor eta-4, eta-3, eta-2, eta-1, and more
preferably eta-5 i.e., non-planar bridging bonding.
[1116] Unsubstituted phenyl does not display sufficient bulkiness
to be included in the definition of bulky groups, due to its
largely planar 3-dimensional shape, whereas, cyclohexane has
sufficient bond angles to constitute a bulky group.
[1117] In addition, these alkyl substituents can also be
functionalized with coordinating groups such as ether, crown ether,
amine, amide, cyano, isonitrile, imine, amidinine, ester, pyridine,
imidazole, pyrrole, pyrazole, oxazole, isooxazole, furan,
pyrimidine, furfuryl, oxirane, aziridine, oxolane, 1,3-dioxolane,
1,4-doxane, 1,3,5-trioxane, pyrrolidine, piperidine, quinuclidine.
They can also be functionalized with groups capable of being
deprotonated, so that with the imidazole also being deprotonated,
they form di-anions, which then can be coordinated to metal
centers. Such groups include, but are not limited to;
cyclopentadiene, pyrrole, beta-diketone, beta-ketoimine,
beta-diimine, alcohol, amine, amide, pyrrole, phenol, carboxylate,
amidinate, guanidinate.
[1118] The effectiveness of tert-butyl and similar three
dimensional bulky groups versus planar groups, such as phenyl, in
creating volatile alkaline earth compounds is illustrated by the
preparation of the barium complex of 2,4,5-triphenylimidazole,
i.e., where R.sup.1.dbd.R.sup.2.dbd.R.sup.3=phenyl, described in
Example 20, where no volatile barium species could be isolated from
the reaction mixture. This is in sharp contrast to the barium
complexes of 2,4,5-tri-tert-butylimidazole and
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole, described in
Examples, 8 and, 16 respectively, which shows exceptional
volatility as illustrated by FIGS. 5 and 16, respectively.
[1119] One of the most well known family of barium compounds for
ALD and CVD applications are the `barocene` compounds, where the
barium ion is coordinated to two multi alkyl functionalized
cyclopentadienyl anions, such as tri-tert-butylcyclopentadienyl
(t-Bu.sub.3 Cp). TGA was used to screen the volatility/thermal
stability of these compounds. In this technique, a sample of the
barium compound is placed in a microbalance pan, which is heated at
a steadily increasing rate under a steady stream of dry inert gas,
such as nitrogen. As the temperature of the sample increases, the
barium compound evaporates at an ever increasing rate, and this
weight loss is detected by the microbalance. Eventually, the
evaporation ceases, and, for barium, there is typically a residue
of involatile material.
[1120] A low level of residue is highly desirable, as this
translates to a controlled evaporation of the barium being
possible, if it is used as a source precursor compound for ALD or
CVD processes. In addition, for CVD or ALD processes, many metal
precursors, such as barium precursors, are dissolved in a solvent,
and this solution is vaporized in a direct liquid injection (DLI)
system. Basically, this comprises delivering a precisely controlled
flow of solution into a vaporizer, where the solution and its
dissolved solute are rapidly heated and vaporized under reduced
pressure. The resulting vapor is then transported into the CVD or
ALD reactor. Typically, there are miniaturized nozzles and narrow
bore tubes used inside the vaporizer at the point where the
solution is nebulized or simply introduced into the vaporization
temperature. If the solute does not fully evaporate and an
involatile residue is formed, these fine bore tubes can become
obstructed, thereby preventing any further flow of solution.
[1121] For these reasons, it is highly desirable for the involatile
residue observed in the TGA experiment to be as low as possible to
avoid the accumulation of obstructing residues, for the best
possible DLI performance. This is especially important in a
commercial manufacturing environment, where such an equipment
failure is prohibitively expensive. It is noted that the TGA
results in FIGS. 5 and 16 for the molecules di-barium
tetra(2,4,5-tri-tert-butylimidazolate) and di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate)
respectively show involatile residues of only 3.53 and 2.99 wt %,
respectively, which are exceedingly low values, indicating the
excellent vaporization characteristics and superior volatility of
the metal imidazolate complexes of this disclosure, compared to
their barocene homologues, such as;
Ba(tBu.sub.3C.sub.5H.sub.2).sub.2(tetrahydrofuran). The latter is
reported to have a TGA involatile residue of 4.2 wt % (Timo
Hatanpaa, Marko Vehkamaki, Ilpo Mutikainen, Jarno Kansikas and
Mikko Ritala "Synthesis and characterization of cyclopentadienyl
complexes of barium: precursors for atomic layer deposition of
BaTiO.sub.3" Dalton Trans., 2004, p. 1181-1188). However, since
this TGA result is of the tetrahydrofuran adduct of the barocene,
rather than pure barocene, it appears artificially low, since some
of the weight loss is incurred simply from loss of tetrahydrofuran.
Accounting for this discrepancy yields a corrected value of
675/603.times.4.2=4.7 wt %, where 675 and 603 represent the
molecular weights of the barocene tetrahydrofuran adduct and pure
barocene, respectively.
[1122] The excellent thermal stability of di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropylimidazolate) is
illustrated in Example 22 and FIG. 22 where, under ALD conditions,
pulses of di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropylimidazolate) are shown
to not thermally degrade on a substrate surface until
>350.degree. C.
[1123] Preferred metal imidazolates include; Di-barium
tetra(2,4,5-tris-t-butylimidazolate); Di-barium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and,
Di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate);
Di-strontium tetra(2,4,5-tris-t-butylimidazolate); Di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dim ethylpropyl)imidazolate);
Di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate); and,
Di-strontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate).
[1124] The present invention is also directed to the synthesis and
use of new and novel barium, strontium, magnesium, radium and
calcium substituted imidazolate-based compounds and their solutions
for vapor delivery upon direct liquid injection, wherein the
substituted, preferably alkyl groups, of the imidazolate ligand
anion are bulky hydrocarbons, such as: tert-butyl, tert-amyl,
adamantly, cyclohexyl, neopentyl, etc.; and can be nitrogen or
oxygen containing alkyl, such as: tertiary amine or ether groups.
Additionally, these new compounds can also coordinate other neutral
ligands, such as ethers or amines or alkoxyamines. Electron
withdrawing groups, such as nitro or acyl, can also be present as a
imidazolate ring substituent.
[1125] While not wishing to be bound by theory, groups, such as
nitro, enhance the coordination of added neutral ligands, such as:
tetrahydrofuran (THF), diglyme, 18-crown-6 crown ether, by
rendering the imidazolate anion less electron donating to barium or
strontium or other alkaline earth metal, and hence, increase the
Lewis acididty of the metal towards added ligands, and hence,
increase their affinity to the metal. Achieving this enhanced
coordination permits the entire barium or strontium compound, with
coordinated ligands, such as THF, to vaporize intact as one
complete compound, rather than releasing this coordinated ligand
first.
[1126] The present invention also includes a novel method of
synthesizing the barium, strontium, magnesium, radium or calcium
compounds by direct metallization of the imidazolate ligands using
a metal reagent, such as barium or strontium hexamethyldisilazane
or barium or strontium hydride, thereby providing an efficient
alternative to using the standard metathesis type of reaction,
where the imidazole is first treated with a metal hydride, such as
sodium hydride, to form a sodium imidazolate, which is then in turn
reacted with a barium or strontium halide, such as barium or
strontium iodide, etc.
[1127] Other novel techniques for synthesizing these new compounds
include, but are not limited to: direct reaction of the imidazole
ligands with barium, strontium, magnesium or calcium metal as a
vapor or as a finely dispersed powder; or by reaction with barium
or strontium metal, etc., in the presence of ammonia; or by
reacting the imidazole ligands with barium metal in the presence of
an amine, such as hexamethyldisilazane, with ammonia. The novel
compounds may also be prepared by electrochemical syntheses.
[1128] Additionally, a wide variety of metals and metalizing agents
can be used to effectively deprotonate the imidazole ligands prior
to reacting with a barium, strontium, magnesium, radium or calcium
source. Such reagents include, but are not limited to: lithium
metal, n-butyl lithium, n-hexyl lithium, sec-butyl lithium,
tert-butyl lithium, lithium diisopropylamide, potassium hydride,
potassium hexamethyldisilazane, sodium hydride, sodium metal,
sodium hexamethyldisilazane, potassium metal, barium metal, sodium
t-butoxide, potassium t-butoxide. Barium sources include, but are
not limited to: barium iodide, barium bromide, barium
trifluoroacetate, barium hexafluoroacetylacetone, barium
trifluoroacetylacetonate, barium acetyacetonate, barium diimine,
barium ketoimine, barium amidinate, barium guanidinate, barium
amide, barium alkoxide, barium amide, barium carbonate, barium
acetate, barium carbonate, barium formate, barium propionate,
barium phenoxide, barium hydroxide, barium fluoride, barium
amidinate, barium amidinine and the strontium, magnesium, radium
and calcium analogs to the barium sources.
[1129] The novel polysubstituted imidazole barium, magnesium,
calcium, radium or strontium compounds of the present invention are
selected from the following structures in Formulae E, F G and H,
where R.sup.1, R.sup.2, R.sup.3 and are each individually selected
to be acyl, formyl, nitro, amido, H, C.sub.1-C.sub.10, primary,
secondary or tertiary alkyl, primary, secondary or tertiary alkene
or alkyne C.sub.1-C.sub.10 alkoxy, C.sub.9-C.sub.20 alkylphenyl,
alkylamine, C.sub.1-C.sub.10 alkyl functionalized with a heteroatom
substituted ring structure, such as: imidazole, pyrrole, pyridine,
furan, pyrimidine, pyrazole, pyrrole, C.sub.1-C.sub.10 alkyl
functionalized with an amide group, and C.sub.1-C.sub.10 alkyl
functionalized with an ester group; and each n independently=0-4,
preferably each n independently=0, 1 or 2. Note that neutral
ligand-free molecules, where n=zero in (L).sub.n to indicate that
there is no (L) ligand coordinated, are also described.
[1130] Mixed complexes can also be created where R.sup.1-3 are
varied differently among imidazolate anions, and then this mixture
is complexed to barium, or other alkaline earth metal, so that the
resulting barium other alkaline earth metal complex represents a
mixture. For example, if two different imidazolate anions I.sup.1
and I.sup.2 are mixed together, and then complexed to barium, three
unique barium complexes can be made; i.e., Ba(I.sup.1).sub.2,
Ba(I.sup.1I.sup.2) and Ba(I.sup.2).sub.2. If three different
imidazolate anions I.sup.1, I.sup.2 and I.sup.3 are mixed, and then
complexed to barium, six barium complexes are formed; i.e.,
Ba(I.sup.1).sub.2, Ba(I.sup.1I.sup.2), Ba(I.sup.1I.sup.3),
Ba(I.sup.2).sub.2, Ba(I.sup.2I.sup.3) and Ba(I.sup.3).sub.2. These
mixtures will be either liquids or highly soluble formulations for
DLI. Also, the groups R.sup.1-3 of one imidazolate anion can be
joined together or can be joined to the R.sup.1-3 groups of another
imidazolate anion to connect the two anions together. The neutral
ligand (L) is selected from aliphatic C.sub.1-C.sub.20 ether or
polyether, crownethers, such as 18-crown-6, amine or polyamine,
alkoxyamine or polyalkoxyamine, amide or polyamide, ester or
polyester, aromatic ether, aromatic ester, aromatic amide, aromatic
amine, pyridine, imidazole, pyridine, pyrazine, furan,
alkylcarbonate or pyrrole. Additionally, groups
R.sup.1,R.sup.2,R.sup.3 and can be linked together to form ring
structures, These ring structures can also be aromatic.
##STR00007##
[1131] It is noteworthy that the dimeric compounds in Formulas F G
and H constitute starting materials from which neutral ligands,
such as diglyme, can be added to create adduct complexes.
[1132] In Formulae E, F, G and H, M is a Group 2 metal selected
from: magnesium, calcium, strontium, barium, radium, preferably
strontium and barium, more preferably barium.
[1133] In addition to the above complexes, while not wishing to be
bound by theory, mixed barium complexes can also be made, where one
polyalkylated imidazolate anion and one other organic or inorganic
anion coordinate to barium to make a complete complex. Examples of
such alternative anions include, but are not limited to:
beta-diketonates, acetates, ketoiminates, diimines, alkoxides,
amides, hydrides, beta-ketoesters, amidinates, guanidinates,
cyclopentadienyl, cyanide, isocyanide, formate, oxalate, malonate,
phenoxide, thiolate, sulfide, nitrate, alkyl, silylalkyl,
fluoroalkyl, aryl, imidazolate. Other alkaline earth metal
complexes, as described above, are also contemplated.
[1134] Several advantages can be achieved through these
metal-containing polyalkylated imidazoles as precursors for
chemical vapor deposition or atomic layer deposition, and these
include:
[1135] An ability to grow ALD and CVD metal oxides and mixed metal
oxides, such as; STO or BST, at high growth rates up to and beyond
one monolayer per cycle;
[1136] An ability to grow crystalline metal oxide and mixed metal
oxides films, such as; STO and BST, directly under ALD or CVD
process conditions;
[1137] An ability to form metal imidazole complexes of
asymmetrically alkylated imidazolates to give low melting or liquid
precursors;
[1138] An ability to form reactive complexes in good yield;
[1139] An ability to form monomeric thermally stable complexes,
particularly strontium and barium complexes, coordinated with one
kind or mixed kind of ligand, thus achieving higher vapor pressure
than that of the known strontium and barium precursors. The known
strontium and barium precursors are either polymeric complexes with
lower vapor pressure or monomeric compounds with low thermal
stability or with relatively high levels of involatile
residues;
[1140] An ability to form highly conformal metal oxide thin films
suited for use in microelectronic devices;
[1141] An ability to enhance the surface reaction between the
metal-containing alkylated imidazolate anion and the surface of a
substrate due to the high chemical reactivity of the complexes;
and,
[1142] An ability to tune the physical properties of these
metal-containing polysubstituted imidazolate anions via a change in
the R.sup.1-3 groups.
[1143] Additionally, metal complexes can also be made by
coordinating two different polysubstituted imidazolate anions to a
metal center, such as barium, such that the two ligands experience
an optimal `fit` or `interlock` with each other and around the
metal, in such a way as to provide an adequate coordination sphere
to create a stable monomeric complex.
[1144] While not wishing to be bound by theory, the molecules of
this disclosure are excellent precursors for use in CVD or ALD
processes for depositing alkaline earth metal oxide containing
films, by reacting them together either sequentially or
simultaneously with an oxidizer, such as: water, alcohol, oxygen,
ozone, nitrous oxide, nitrogen dioxide, hydrogen peroxide or
combinations thereof either in the presence or absence of an
applied plasma discharge. Additionally, barium and strontium
molecules of this disclosure can be reacted with a titanium
precursor, such as: a titanium alkoxy/diketonate, titanium
alkoxy/ketoester, titanium alkoxide, titanium cyclopentdienyl,
titanium amide titanium imidazolate containing precursor, titanium
pyrrolyl containing precursor or combinations thereof, in a CVD,
pulsed CVD or ALD mode or hydride pulsed CVD/ALD process to deposit
BST (barium strontium titanate) films, which are highly prized, due
to their high dielectric constant. Additionally, the barium
complexes of this disclosure can be reacted with strontium
ketoiminates and titanium precursors, such as: a titanium
alkoxy/diketonate, titanium alkoxy/ketoester, titanium alkoxide,
titanium cyclopentdienyl, titanium amide titanium imidazolate
containing precursor, titanium pyrrolyl containing precursor or
combinations thereof, in a CVD, pulsed CVD or ALD or hydride pulsed
CVD/ALD mode to deposit a BST film.
[1145] These new precursor molecules are able to deliver
exceptionally high deposition rates, due to their ability to engage
in highly novel modes of surface adsorption and reaction. Thus,
when using the novel precursor, a deposition rate of >2.5
Angstroms of strontium oxide per cycle at 350.degree. C. is
achieved representing .about.5 times a typical growth rate. Such an
enhancement in growth per cycle is critically important, because it
permits a greater throughput of wafers per unit time in commercial
production, thus representing a substantial saving. Further, it is
believed that the novel imidazolate ligands of this disclosure will
similarly permit enhanced growth rates of other metals and metal
containing films.
[1146] The precursors of this disclosure are highly suitable for
use as volatile precursors for ALD, CVD, pulsed CVD, plasma
enhanced ALD (PEALD) or plasma enhanced CVD (PECVD) for the
manufacture of semiconductor type microelectronic devices, such as
microcapacitor cells for memory applications such as DRAM devices.
They are also highly useful for the manufacture of pyrodetector
devices.
[1147] The precursors of this application can also readily be
dissolved into a wide range of solvents, and the resulting
solutions used in DLI mode to provide a vapor stream of these
precursors into an ALD or CVD reactor. Being of low melting point,
they are exceptionally soluble, including solubility in:
alkylethers, alkylamines, alkoxyamines, aromatic ethers, aromatic
amines, amides, esters and hydrocarbon solvents. The latter two
species are particularly attractive, due to their ability to be
dried to sub-ppm levels of water. Solvents that are exemplary of
the solvents that can be used in the present invention are amino
ethers, such as BL-19, glymes such as
dipropyleneglycoldimethylether, e.g., DPGDME,
pentamethyl-diethylene triamine, N,N-dimethylcyclohexylamine,
N-methyldicyclohexylamine, Dimethyl-4-morpholine ethamine,
Anisole(methoxybenzene), Phenetole (ethoxybenzene), toluene,
mesitylene, cumene (isopropylbenzene), p-cymene (4-isopropyl
toluene), 1,3-diisopropylbenzene, octane, dodecane,
1,2,4-trimethylcyclohexane, n-butylcyclohexane, and
decahydronaphthalene (decalin). The precursors of this application
can also be stored and used in stainless steel containers.
[1148] The precursors of this application can also be mixed with
other suitable metal precursors, and the mixture used to deliver
both metals simultaneously for the growth of a binary metal oxide
or nitride films. For example, strontium precursors of this
disclosure can be mixed with suitable titanium precursors,
including imidazolate based titanium precursors, for the growth of
strontium titanate (STO) films. Similarly, barium precursors of
this disclosure can be mixed with suitable strontium precursors,
including imadazolate based strontium precursors, with suitable
titanium precursors, including imidazolate precursors, for the
growth of barium strontium titanate (BST) films. Similarly, barium
precursors of this disclosure can be be mixed with suitable
titanium precursors, including imidazolate based titanium
precursors, for the growth of barium titanate (BTO) films.
[1149] The present invention is also a method of depositing a metal
containing film by ALD or CVD comprising the use of the metal
imidazolate structures of the present invention described
above.
[1150] Preferably, the present invention includes a method of
depositing a metal containing film by reacting a metal imidazolate
structure of the present invention with an oxidant selected from
the group consisting of water, alcohol, oxygen, ozone, nitrous
oxide, nitrogen dioxide, hydrogen peroxide or combinations thereof
to grow a metal containing film selected from the group consisting
of barium oxide, strontium oxide, magnesium oxide, calcium oxide or
radium oxide and mixtures thereof, using a reactor pressure between
0.001-1000 Torr and a temperature from 0-1000.degree. C.
[1151] More preferably, this method results in a deposition of
barium oxide of >1 Angstrom per cycle. Even more preferably, the
deposition of barium oxide is >1.5 Angstrom per cycle. Still
more preferably, the deposition of barium oxide is >2 Angstrom
per cycle.
[1152] Alternately, the method results in the deposition of
strontium oxide of >1 Angstrom per cycle. Preferably, the
deposition of strontium oxide is >1.5 Angstrom per cycle. More
preferably, the deposition of strontiumium oxide is >2 Angstrom
per cycle.
[1153] In one embodiment, the method of the present invention
includes reacting a Ba and Sr imidazolate structure of the present
invention with alternating pulses of titanium precursors selected
from the group consisting of titanium alkoxide, titanium
alkoxide/diketonate, titanium cyclopentadienyl, titanium amide,
titanium imidazolate and mixtures thereof in an ALD or pulsed CVD
mode to grow BST films.
[1154] In another embodiment, the present invention is a method of
reacting a Sr imidazolate structure of the present invention with
alternating pulses of titanium precursors selected from the group
consisting of titanium alkoxide, titanium alkoxide/diketonate,
titanium cyclopentadienyl, titanium amide titanium imidazolate and
mixtures thereof in an ALD or pulsed CVD mode to grow STO
films.
[1155] A further embodiment is a method of reacting a Ba
imidazolate structure of the present invention with alternating
pulses of titanium precursors selected from the group consisting of
titanium alkoxide, titanium alkoxide/diketonate, titanium
alkoxy/ketoester, titanium cyclopentadienyl, titanium amide
titanium imidazolate and mixtures thereof in an ALD or pulsed CVD
mode to grow BTO films.
[1156] A still further embodiment is a method of reacting a barium
imidazolate structure of the present invention with a strontium
compound selected from the group consisting of strontium
ketoiminate, strontium diketonate and mixtures thereof and a
titanium compound selected from the group consisting of titanium
alkoxide, titanium alkoxide/diketonate, titanium alkoxy/ketoester,
titanium cyclopentadienyl, titanium amide and mixtures thereof, in
an ALD, CVD or pulsed CVD to grow films of BST.
[1157] Yet another embodiment is a method of reacting an
imidazolate structure of claim 13 with halide gases selected from
the group consisting of HCl, HF, SiCl.sub.4, HBr and mixtures
thereof to grow MX.sub.2 where X=halide and M is selected from the
group consisting of Ba, Sr, Mg, Ca, Ra and mixtures thereof, in an
ALD, CVD or pulsed CVD mode.
[1158] A method of synthesizing an imidazolate structure of the
present invention by direct metallization of an imidazole with a
metal reagent selected from the group consisting of n-butyl
lithium, n-hexyl lithium, sec-butyl lithium, tert-butyl lithium,
lithium diisopropylamide, potassium hydride, sodium hydride, sodium
metal, potassium metal, sodium t-butoxide, potassium t-butoxide,
potassium hexamethyldisilazane, sodium hexamethyldisilazane and
then reacting the resulting product with a reactant selected from
the group consisting of: alkaline earth metal iodide, alkaline
earth metal acetate, alkaline earth metal carboxylate, alkaline
earth metal carbonate, alkaline earth metal formate, alkaline earth
metal bromide, alkaline earth metal trifluoroacetate, alkaline
earth metal hexafluoroacetylacetone, alkaline earth metal
trifluoroacetylacetonate, alkaline earth metal acetyacetonate,
alkaline earth metal diimine, alkaline earth metal ketoimine,
alkaline earth metal amidinate, alkaline earth metal guanidinate
and mixtures thereof.
[1159] A method of directly synthesizing an imidazolate structure
of the present invention by reacting a polylalkylated imidazole
using a reagent selected from the group consisting of: an alkaline
earth metal amide, alkaline earth metal phenoxide, alkaline earth
metal hydroxide, alkaline earth metal alkyl, alkaline earth metal
aryl and mixtures thereof.
[1160] In an alternate embodiment, the present invention is a
method of synthesizing an imidazolate structure of the present
invention by reaction of an imidazole with an alkaline earth metal
in the presence of ammonia.
[1161] A further alternate is a method of synthesizing an
imidazolate structure of the present invention by reacting an
imidazole with an alkaline earth metal in the presence of an amine
with ammonia.
[1162] The present invention is also a method to grow dielectric
films selected from the group consisting of: STO and BST using the
mixture of metal imidazolates of the present invention to form
micro-electronic devices selected form the group consisting of
dynamic random access memory (DRAM) memory cells and pyrometric
devices.
[1163] Alternately, the present invention is a method of
manufacturing microelectronic devices selected from the group
consisting of: non-volatile ferroelectric microelectronic memory
devices, display phosphors for electroluminescent displays, high Tc
superconducting devices using the imidazolate structures of the
present invention.
[1164] In yet another embodiment, the present invention is a method
of growing a metal oxide or nitride film by ALD or CVD comprising;
providing a barium or strontium imidazolate structure of the
present invention in conjunction with titanium sources dissolved in
a solvent selected from the group consisting of: an ether,
aminoether, amide, ester, aromatic or hydrocarbon solvent and
delivering the resulting solution by a DLI system to provide a
vapor stream of the resulting solution to grow the metal oxide or
nitride film by ALD or CVD.
EXAMPLES
Example 1
Synthesis of 2,5-di-tertbutylimidazole
[1165] 5.44 g (0.04 moles) of 2,2-dimethylpropanimidamide
hydrochloride were mixed with 7.2 g (0.04 moles) of
1-bromopinacolone and 11.2 g of triethylamine in 16.0 g of
diethylformamide (DEF) and stirred at room temperature for 7 days.
The reaction mixture was then poured into water and extracted three
times with 50 ml units of hexane. The hexane fractions were
combined and washed three times with 50 ml aliquots of water. The
hexane layer was then stirred with 5 g of anhydrous magnesium
sulfate over night. The hexane was then removed by vacuum down to a
volume of 5 ml to yield a fine suspension. This was filtered and
the resulting solid washed with fresh hexane to yield 4.22 g (59%
theoretical) of colorless fine crystalline product, 99% pure by Gas
Chromatography Mass Spectrometry gave a parent ion at 180 amu.
Structure confirmed by X-ray crystallography (see FIG. 1)
GCMS.
[1166] .sup.1H NMR: (500 MHz, D.sub.8 THF): .delta.=1.23 (5, 9H),
.delta.=1.3 (5, 9H), .delta.=6.48 (s, 1H), .delta.=10 (bs, 1H).
[1167] .sup.1H NMR: (500 MHz, D.sub.8 THF): .delta.=30.3 (s, 3C),
.delta.=30.8 (s, 3C), .delta.=32.1 (s, 1C), .delta.=33.6 (s, 1C),
.delta.=111 (bs, 1C), .delta.=148 (bs, 1C), .delta.=155 (s,
1C).
X-ray
Example 2
Synthesis of 2,2,5,5-Tetramethyl-3-hexanone
[1168] 2-chloro-2-methyl propane (75 g, 0.8 mol) was slowly added
to magnesium pellets (19.5 g, 0.8 mol) in 800 mL of THF to make the
Grignard reagent, tBuMgCl. This was added slowly to a mixture of
cuprous chloride (49.5 g, 0.50 mol) and tertbutylacetylchloride
(67.25 g, 0.50 mol), cooled to -50.degree. C. in dry ice. After
addition, the mixture was allowed to warm up to room temperature
overnight. Most of the THF was removed by decreased pressure,
followed by the addition of 500 mL of hexanes and 200 mL of 2M HCl.
This mixture was filtered to remove the solid byproducts. The
aqueous layer was washed 3.times. with 100 mL of hexanes, the
hexanes layer washed 3.times. with 200 mL of 2M HCl, 2.times. with
200 mL of NaHCO.sub.3/water, 1.times. with 200 mL of water, and
finally 1.times. with 200 mL of NaCl/water. The product mixture was
then dried for an hour in MgSO.sub.4, which was subsequently
removed by filtration. The hexane was then removed by atmospheric
distillation.
[1169] Yield=61 g (78% of theoretical).
[1170] Product identified by Mass Spectrum parent ion of 156 mu,
NMR consistent with literature: D. P Bauer, J. Org. Chem., Vol. 40,
No. 13, 1975, 1990-1992.
Example 3
Synthesis of 4-Bromo-2,2,5,5-tetramethyl-3-hexanone
[1171] 24 g of N-bromosuccinimide (0.1344 mol) was added to 10 g of
2,2,5,5-Tetramethyl-3-hexanone (0.064 mol) in 50 mL of
trimethylacetonitrile. To this mixture, 10 g of ammonium acetate
(0.1344 mol) was added within 5 minutes. This mixture was refluxed
overnight then filtered. To the filtrate, 24 g of
N-bromosuccinimide (0.1344 mol) and 10 g of ammonium acetate
(0.1344 mol) was added, then refluxed for 5 hours. The reaction
mixture was then cooled, 600 mL of water added, and the resulting
mixture then filtered. The aqueous layer was washed three times
with 50 ml of hexanes. The hexane fractions were then combined,
washed three times with 50 ml of with water, then dried with
anhydrous magnesium sulfate. Product was collected by distilling
off the hexane at atmospheric pressure.
[1172] Yield 11.6 g, (77% of theoretical)
[1173] Product identified by Mass Spectrum parent ion of 236 mu,
NMR consistent with literature: D. P Bauer, J. Org. Chem., Vol. 40,
No. 13, 1975, 1990-1992; Procedure Reference: K. Tanemura, Chem.
Commun. 2004, 470-471.
Example 4
Synthesis of 4-hydroxy-2,2,5,5-tetramethyl-3-hexanone
[1174] 5 g (0.125 mol) of sodium hydroxide powder was added to 11.6
g (0.05 mol) of 4-Bromo-2,2,5,5-tetramethyl-3-hexanone in 10 g of
dry diethylformamide. This reaction mixture was heated to
110.degree. C. for 2 hours, cooled to room temperature and 600 mL
of water and 200 mL of hexanes added. The hexane layer was
collected and the aqueous layer was washed three times with 50 ml
of additional hexanes. The hexanes fractions were then combined,
washed three times with 50 ml water, then dried with MgSO.sub.4.
The product was collected as a crystalline solid after after
hexanes removal by atmospheric distillation.
[1175] Yield=5.2 g, (60% of theoretical).
[1176] Product identified by Mass Spectrum Parent ion of 172
mu.
Example 5
Synthesis of 2,2,5,5-tetramethyl-3,4-hexandione
[1177] 7.8 g (0.045 moles) of
2,2,5,5-tetramethyl-4-hydroxy-3-hexanone were dissolved in 90 ml of
hexane and stirred vigorously with 157 ml of 1M aqueous potassium
permanganate solution containing 1.8 g (0.045 moles) of sodium
hydroxide. This mixture was then refluxed overnight. The mixture
was then cooled to room temperature and the hexane layer separated.
The aqueous layer was then extracted three times with 50 ml of
hexane. The hexane solutions were then combined and washed three
times with 50 ml of pure water before drying over anhydrous
magnesium sulfate. The mixture was then filtered and the hexane
distilled off at atmospheric pressure to yield 6.3 g of
2,2,5,5-tetramethyl-3,4-hexanedione (82% of theoretical).
[1178] Product identified by GCMS parent ion 170 mu, consistent
with literature results G. A. Olah and A. Wu, J. Org. Chem., 56,
904-906 (1991).
Example 6
Synthesis of 2,4,5-tri-tert-butylimidazole
[1179] 1.6 g (0.0094 moles) of 2,2,5,5-tetramethyl-3,4-hexanedione
were mixed with 2.9 g (0.037 moles) of ammonium acetate, 3.4 g
(0.057 moles) of acetic acid and 1.6 g (0.019 moles) of pivaldehyde
and heated to 13.degree. C. for 72 hrs in a sealed container. This
mixture was then cooled and slowly added to an excess of aqueous
saturated sodium bicarbonate solution. The resulting mixture was
extracted with 3.times.50 ml of hexane. The hexane fractions were
combined, washed three time with 20 ml aliquots of pure water, then
dried over anhydrous sodium sulfate. Evaporation of hexane yielded
crude 2,4,5-tri-tert-butylimidazole as its hydrate (two molecules
of imidazole per water molecule). This product was then dried by
refluxing it in 50 ml of hexamethyldisilazane for 48 hrs.
[1180] The hexamethyldisilazane and hexamethyldisiloxane (formed
from the drying process) was then evaporated, and the resulting
solid sublimed at 60 C to give colorless crystals, yield 1.3 g (58%
of theoretical).
[1181] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=1.24 (s,
9H), .delta.=1.26 (s, 9H), .delta.=1.65 (s, 9H), .delta.=8.07 (bs,
1H).
[1182] .sup.13C NMR: (500 MHz, C.sub.6D.sub.6): .delta.=30.0 (s,
3C), .delta.=31.70 (s, 1C), .delta.=32.26 (s, 3C), .delta.=32.87
(s, 1C), .delta.=33.18 (s, 3C), .delta.=34.07 (s, 1C),
.delta.=130.16 (s, 1C), .delta.=143.84 (s, 1C), .delta.=149.21 (s,
1C).
[1183] Mass spectrum: 236 mu (parent ion).
[1184] Structure of the of 2,4,5-tri-tert-butylimidazole was also
confirmed by X-ray crystallography, see FIG. 2.
[1185] In addition to the synthesis routes of this disclosure that
are used to prepare sterically hindered imidazoles, a plurality of
other routes are anticipated. These include conceptually
deconstructing the five membered imidazole ring by breaking
specific ring bonds to yield fragments bearing the required bulky
groups. A synthesis of these fragments is then developed followed
by a means of coupling them together to form the final imidazole
product.
Example 7
Synthesis of barium
bis(2,4,5-tri-tert-butylimidazolate)(tetrahydrofuran)
[1186] Under an atmosphere of nitrogen, 0.292 g (0.00124 moles) of
dry 2,4,5-tri-tert-butylimidazole were dissolved into 5 ml of dry
tetrahydrofuran with stirring. To this was added a solution of 0.37
g (0.00062 moles) of barium bis(hexamethyldisilazane)bis
(tetrahydrofuran) dissolved in 5 ml of tetrahydrofuran. This
mixture was stirred for 3 hours at room temperature. The
tetrahydrofuran and by product hexamethyldisilazane were then
evaporated by application of vacuum and the resulting white solid
dissolved into 1 ml of dry hexane. The resulting solution was then
concentrated by boiling to 0.5 ml and allowed to stand at room
temperature. This yielded 0.3 g (83% of theoretical) of barium
bis(2,4,5-tri-tert-butylimidazolate)(tetrahydrofuran) as colorless
prisms. Structure confirmed by single crystal X-ray diffraction,
see FIG. 3.
[1187] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=1.29 (m,
4H), .delta.=1.49 (s, 18H), .delta.=1.59 (m, 36H), .delta.=3.82 (m,
4H).
[1188] .sup.13C NMR: (500 MHz, C.sub.6D.sub.6): .delta.=25.72 (s,
2C), .delta.=30.1 (s, 1C), .delta.=31.5 (s, 3C), .delta.=33.7 (s,
6C), .delta.=34.26 (s, 2C), .delta.=69.95 (s, 2C), .delta.=147.75
(s, 1C), .delta.=159.77 (s, 1C).
Example 8
Synthesis of di-barium tetra(2,4,5-tri-tert-butylimidazolate)
[1189] Under an atmosphere of nitrogen, 1.18 g (0.005 moles) of
2,4,5-tri-tert-butylimidazole were dissolved in 10 ml of dry hexane
and 0.4 g (0.0025 moles) of bis[2-(N,N-dimethylamino)ethyl]ether.
To this mixture, a solution of 1.5 g (0.0025 moles) of barium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 10 ml of
dry hexane was added dropwise and the mixture stirred overnight.
The solvents were then removed under vacuum and the resulting solid
sublimed twice at 160 C to yield 0.6 g (47% of theoretical) of snow
white solid, melting point (MPt) 150.degree. C., characterized by
X-ray crystallography, see FIG. 4.
[1190] The evaporation characteristics of di-barium
tetra(2,4,5-tri-tert-butylimidazolate) was determined by TGA
resulting in only 3.5 weight % residue, as shown in FIG. 5.
[1191] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=1.46 (6,
36H), .delta.=1.50 (s, 18H)
Example 9
Synthesis of di-strontium
tetra(2,4,5-tri-tert-butlyimidazolate)
[1192] Under an atmosphere of nitrogen, 1.18 g (0.005 moles) of
2,4,5-tri-tert-butylimidazole were dissolved in 10 ml of dry
tetrahydrofuran. 1.38 g (0.0025 moles) of strontium
bis(hexamethyldisilazane)bis(tetrahydrofuran) were then dissolved
in 10 ml of dry tetrahydrofuran and this solution was added
dropwise, with stirring, to the 2,4,5-tri-tert-butylimidazole
solution and the resulting mixture stirred overnight. The solvents
were then removed under vacuum and the resulting solid sublimed
twice at 150 C to yield 0.5 g (36% of theoretical) of snow white
solid, MPt 149.degree. C., characterized by X-ray crystallography,
see FIG. 6.
Example 10
Synthesis of 3,3,6,6-tetramethyl-4,5-octanedione
[1193] Under a blanket of nitrogen, 18.72 g, (0.78 moles) of
magnesium turnings in 780 ml of tetrahydrofuran were activated by
the addition of 0.5 ml of 1,2-dibromoethane. 2-chloro-2-methyl
butane (96 mL, 0.78 mol) were then slowly added resulting in the
gradual formation of Grignard reagent, accompanied by a reaction
exotherm. This Grignard reagent was then slowly added to a mixture
of 112 g (0.78 mol) of copper bromide and 67 g (0.78 mol) of
lithium bromide dissolved in 340 mL of tetrahydrofuran, cooled to
-65.degree. C. After all the Grignard was added and the temperature
stabilized at -65.degree. C., 26 mL (0.30 mol) of oxalyl chloride
in 100 mL of tetrahydrofuran was added slowly, maintaining mixture
temperature at -65.degree. C. The resulting mixture was stirred for
an hour at -65.degree. C., then warmed up to room temperature
overnight. 90% of the tetrahydrofuran THF was then removed by
vacuum. 500 ml of hexane and 300 mL of saturated aqueous ammonium
chloride were then added to the resultant slurry, and the hexane
layer separated. The aqueous layer was then further extracted with
three 200 ml lots of hexane. The combined hexane layers were then
washed with 200 mL of water, then dried over 10 g of anhydrous
magnesium sulfate for one hour. The magnesium sulfate was then
filtered off and the hexane distilled off at atmospheric pressure
to yield the crude product diketone as an orange red liquid.
Yield=32.2 g (54% of theoretical)
[1194] Mass spectrum: 198 mu (parent ion).
Example 11
Synthesis of 2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole
[1195] A mixture of 32.3 g (0.163 mol) of
3,6,6-tetramethyl-4,5-octanedione, 50 g (0.652 mol) of ammonium
acetate, 36 mL (0.326 mol) of pivaldehyde and 56 mL (0.978 mol) of
acetic acid was heated to 200.degree. C. in a sealed stainless
steel vessel for 3 days. The resulting product mixture was
neutralized with sodium bicarbonate solution, then extracted with
four 200 ml lots of hexane. The combined hexane layers were washed
3.times. with 100 mL of water then 100 ml of saturated sodium
chloride solution. 10 g of anhydrous magnesium sulfate was added
and stirred overnight. Filtration followed by removal of hexane by
vacuum yielded the crude product as a yellow oil. Yield 31.5 g (73%
of theoretical).
[1196] Mass spectrum: 264 mu (parent ion).
Example 12
Synthesis of di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate)
[1197] Under a blanket of nitrogen, 1.13 g ((0.002 moles) of
strontium bis(hexamethyldisilylamide)bis(tetrahydrofuran) dissolved
in 20 ml of dry tetrahydrofuran were added dropwise over a five
minute period at room temperature to 1.08 g (0.004 moles) of
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole dissolved in 20
ml of dry tetrahydrofuran and the resulting mixture stirred for two
hours. The THF and by-product hexamethyldisilazane were then
removed under vacuum. The resulting crude product was then
distilled under vacuum at 200 C to yield 0.5 g of a colorless
glassy solid. This was recrystallized in hexane to yield colorless
prisms, MPt 103C.
[1198] Yield=40% of theoretical.
[1199] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.82 (t,
12H), .delta.=1.41 (s, 24H), .delta.=1.54 (s, 18H), .delta.=1.74
(q, 8H). Structure confirmed by single crystal X-ray analysis, see
FIG. 8.
Example 13
Synthesis of di-barium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate)
[1200] Under an atmosphere of dry nitrogen, a solution of 6.0 g
(0.01 moles) of barium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 15 ml of
dry tetrahydrofuran were added dropwise to 5.28 g (0.02 moles) of
2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazole dissolved in 30
ml of dry tetrahydrofuran. The resulting mixture was stirred
overnight, after which the solvent and hexamethyldisilazane were
removed by vacuum. The resulting waxy solid was then vacuum
distilled at to 195.degree. C. to give a clear colorless liquid
distillate of di-barium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl) imidazolate), which
solidified after standing overnight. Yield 4.8 g (78%). Structure
proven by X-ray, FIG. 10. MPt 65.3.degree. C.
[1201] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.85 (t,
12H), .delta.=1.39 (s, 24H), .delta.=1.53 (s, 18H),
.delta.=1.76-1.81 (q, 8H).
Example 14
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole
[1202] 15 g (0.09 moles) of 2,2,5,5-tetramethyl-3,4-hexanedione
were mixed with 42 g (0.55 moles) of ammonium acetate, 32 g (0.53
moles) of acetic acid and 20.52 g (0.18 moles) of
2,2-dimethylvaleraldehyde and heated to 20.degree. C. for 48 hrs in
a sealed container. This mixture was then cooled to 90.degree. C.,
and approximately 90% of the acetic acid distilled off under
reduced pressure. The residual crude product was then diluted with
approximately 100 ml of hexane and neutralized to pH 7 using
saturated aqueous sodium bicarbonate solution with strong stirring.
The resulting mixture was extracted with 3.times.200 ml of hexane.
The hexane fractions were combined, washed three times with 50 ml
aliquots of pure water, then dried over anhydrous sodium sulfate.
After overnight stirring, the solution was then decanted off the
magnesium sulfate and then stood over molecular sieves overnight.
The molecular sieves were then removed, the hexane distilled off at
atmospheric pressure, and the resulting product then distilled at
150.degree. C. under 100 mTorr of pressure. Yield=13.5 g (57% of
theoretical) of 2-(1,1-dim
ethylbutyl)-4,5-di-tert-butylimidazole.
[1203] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.79 (t,
3H), .delta.=1.19-1.23 (m, 2H), .delta.=1.24 (s, 9H), .delta.=1.26
(s, 9H), .delta.=1.53-1.57 (m, 2H), .delta.=1.65 (s, 6H).
Example 15
Di-strontium-tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate)
[1204] Under an atmosphere of dry nitrogen, a solution of 5.54 g
(0.01 moles) of strontium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 15 ml of
dry tetrahydrofuran were added dropwise to 5.06 g (0.019 moles) of
2-tert-butyl-4,5-di-(1,1-dimethylbutyl)imidazole dissolved in 30 ml
of dry tetrahydrofuran. The resulting mixture was stirred for 12
days at room temperature, after which the solvent and
hexamethyldisilazane were removed by vacuum. The resulting crude
product was vacuum distilled at 100 mTorr, collecting the main
fraction of
di-strontium-tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate)
from 150 to 205.degree. C. as a clear liquid, which solidified into
a glass at room temperature, slowly crystallizing overnight. Yield
3.5 g (60% of theoretical). Structure proven by single crystal
X-ray diffraction using a crystal grown from a hexane solution, see
FIG. 13. TGA/DSC showed a melting point of 99.8.degree. C. and an
involatile residue of 8.17 wt %.
[1205] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.91 (t,
6H), .delta.=1.27-1.32 (m, 4H), .delta.=1.45 (s, 36H), .delta.=1.54
(s, 12H), 1.75-1.80 (m, 4H).
Example 16
Di-barium-tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate)
[1206] Under an atmosphere of dry nitrogen, a solution of 6.03 g
(0.01 moles) of barium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 15 ml of
dry tetrahydrofuran were added dropwise to 5.28 g (0.019 moles) of
2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazole dissolved in 30 ml
of dry tetrahydrofuran. The resulting mixture was stirred for 7
days at room temperature, after which the solvent and
hexamethyldisilazane were removed by vacuum. The resulting crude
product vacuum distilled at 50 mTorr, collecting the main fraction
of
di-strontium-tetra(2-(1,1-dimethylbutyl)-4,5-di-tert-butylimidazolate)
from 170 to 180.degree. C. as a clear liquid, which crystallized
upon cooling to room temperature. Yield 4.8 g (72% of theoretical).
Structure proven by single crystal X-ray diffraction using a
crystal grown from a hexane solution, see FIG. 15. TGA/DSC showed a
melting point of 128.degree. C. and an involatile residue of only
2.99 wt %.
[1207] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.92 (t,
6H), .delta.=1.28-1.4 (m, 4H), .delta.=1.46 (s, 36H), .delta.=1.5
(s, 12H), .delta.=1.73-1.82 (m, 4H).
Example 17
Synthesis of
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole
[1208] 20 g (0.1 moles) of 3,3,6,6-tetramethyl-4,5-octanedione were
mixed with 46 g (0.6 moles) of ammonium acetate, 30 g (0.6 moles)
of acetic acid and 11.4 g (0.1 moles) of 2,2-dimethylvaleraldehyde
and heated to 200.degree. C. for 48 hrs in a sealed container. This
mixture was then cooled to 90.degree. C., and approximately 90% of
the acetic acid distilled off under reduced pressure. The residual
crude product was then diluted with approximately 100 ml of hexane
and neutralized to pH 7 using saturated aqueous sodium bicarbonate
solution with strong stirring. The resulting mixture was extracted
with 3.times.200 ml of hexane. The hexane fractions were combined,
washed three times with 50 ml aliquots of pure water, then dried
over anhydrous sodium sulfate. After overnight stirring, the
solution was then decanted off the magnesium sulfate, and dried
molecular sieves were added. After overnight standing the molecular
sieves were removed, the hexane dstilled off at atmospheric
pressure, and the resulting product then distilled at 150.degree.
C. under 100 mTorr of pressure. Yield=15 g (51% of theoretical) of
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole.
[1209] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.69 (t,
3H), .delta.=0.82 (t, 3H), .delta.=1.0 (t, 3H), .delta.=1.15-1.2
(m, 2H). .delta.=1.19 (s, 6H), .delta.=1.25 (s, 6H),
.delta.=1.52-1.60 (m, 4H), .delta.=1.59 (s, 6H), .delta.=1.96-2.0
(q, 2H), .delta.=8.0 (bs, 1H).
Example 18
Synthesis of distrontium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate)
[1210] Under an atmosphere of dry nitrogen, a solution of 7.46 g
(0.0135 moles) of strontium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 50 ml of
dry tetrahydrofuran were added dropwise to 7.88 gg (0.0269 moles)
of 2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole
dissolved in 50 ml of dry tetrahydrofuran. The resulting mixture
was stirred for 2 days at room temperature, after which the solvent
and hexamethyldisilazane were removed by vacuum. The resulting
crude product vacuum distilled at 50 mTorr, collecting the main
fraction of di-strontium-tetra(2-(1,1-dim
ethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate)
[1211] .sup.1H NMR: (500 MHz, C.sub.6D.sub.6): .delta.=0.77 (t,
12H), .delta.=0.87 (t, 6H), .delta.=1.1-1.23 (m, 4H), .delta.=1.38
(s, 24H), .delta.=1.51 (s, 12H), .delta.=1.62-1.75 (m, 12H).
Example 19
Synthesis of dibarium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate)
[1212] Under an atmosphere of dry nitrogen, a solution of 7.0 g
(0.0116 moles) of barium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 50 ml of
dry tetrahydrofuran were added dropwise to 8.11 g (0.0277 moles) of
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole (19%
excess) dissolved in 50 ml of dry tetrahydrofuran. The resulting
mixture was stirred for 2 days at room temperature, after which the
solvent and hexamethyldisilazane were removed by vacuum. The
product and excess
2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazole were
then vacuum distilled out of the crude reaction product at
200.degree. C./50 mTorr. The excess imidazole ligand was then
removed by vacuum distillation at 120.degree. C. to yield di-barium
tetra(2-(1,1-dimethylbutyl)-4,5-di-(1,1-dimethylpropyl)imidazolate)
as a thick viscous amber liquid, which slowly crystallized upon
standing. Mpt 36.degree. C., yield 5.6 g (62%). Recrystallization
from hexane yielded colorless crystals, MPt 56.4.degree. C., TGA
residue 6.77 wt %. .sup.1H NMR: (500 MHz, C.sub.6D.sub.6):
.delta.=0.84 (t, 12H), .delta.=0.93 (t, 6H), .delta.=1.22-1.35 (m,
4H), .delta.=1.39 (s, 24H), .delta.=1.53 (s, 12H), .delta.=1.7-1.8
(m, 12H)
Example 20
Synthesis of barium bis(2,4,5-tri-phenylylimidazolate)
[1213] Under an atmosphere of dry nitrogen, 0.6 g (0.002 moles) of
2,4,5-triphenylimidazole were dissolved in 10 ml of dry
tetrahydrofuran. A solution of 0.6 g (0.001 moles) of barium
bis(hexamethyldisilazane)bis(tetrahydrofuran) dissolved in 10 ml of
dry tetrahydrofuran was then prepared and added to the
2,4,5-triphenylimidazole solution and the resulting mixture stirred
overnight. The solvent and hexamethyldisilazane were then removed
under vacuum, yielding a thick viscous tar, which eventually
solidified. Application of vacuum and heat >200.degree. C. did
not liberate any volatile products.
Example 21
[1214] ALD of Strontium oxide using di-strontium
tetra(2-tert-butyl-4,5-di(1,1-dimethylpropyl) imidazolate)
[1215] Under an atmosphere of nitrogen, 50 g of di-strontium
tetra(2-tert-butyl-4,5-di-(1,1-dimethylpropyl)imidazolate) were
loaded into a dry stainless steel container. This container was
then heated to 170.degree. C., and argon carrier gas was
intermittently flowed through it at a rate of 100 sccm to achieve
ALD `pulses` of the precursor, varying from 6 to 16 seconds. These
precursor pulses were directed into an ALD chamber containing a
silicon substrate heated from 300-400.degree. C. Each precursor
pulse was followed by a purging pulse of argon gas, then followed
with a pulse of ozone. FIG. 18 shows the results achieved for SrO
deposition at 350.degree. C. substrate temperature using 8 and 10
second precursor pulses, which shows a linear ALD relationship
between film growth and total number of precursor pulses, giving a
growth rate of 2.3 A/cycle of SrO. Using this same deposition
procedure at a substrate temperature of 375.degree. C. yielded the
SrO film shown in FIG. 20, the upper portion of which is clearly
crystalline and the lower portion of which is amorphous. Note that
a titanium oxide protective layer is deposited on top of the SrO.
In the crystalline region, it is seen that there are 24 layers of
SrO per 66 Angstroms, to yield a spacing of 2.75 Angstroms,
consistent with (001) SrO. XPS, shown in FIG. 21, which indicates
the film to be substantially pure strontium oxide. The low level of
carbon throughout the film is partially attributable to post
deposition reaction with atmospheric carbon dioxide to yield
strontium carbonate.
Example 22
[1216] ALD thermal stability demonstration for di-strontium
tetra(2-tert-butyl-4,5-di-tert-amylimidazolate)
[1217] 100 cycles of 5 seconds precursor/10 seconds argon purge
using argon, as in Example 15, but no ozone was used to oxidize
adsorbed precursor. Substrates were processed from 250-400.degree.
C. As FIG. 22 shows, there is no significant thermal deposition
occurring until >350.degree. C., indicating excellent stability
for ALD.
* * * * *