U.S. patent application number 16/861275 was filed with the patent office on 2020-10-15 for heterogeneous wet synthesis process for preparation of high purity tungsten pentahalide.
The applicant listed for this patent is American Air Liquide, Inc., L'Air Liquide, Societe Anonyme pour I'Etude et I'Exploitation des Procedes Georges Claude. Invention is credited to Claudia FAFARD, Jean-Marc GIRARD, Guillaume HUSSON, Feng LI, Yumin LIU, Grigory NIKIFOROV, Bin SUI, Zhiwen WAN, Stefan WIESE.
Application Number | 20200325036 16/861275 |
Document ID | / |
Family ID | 1000004925948 |
Filed Date | 2020-10-15 |
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United States Patent
Application |
20200325036 |
Kind Code |
A1 |
LIU; Yumin ; et al. |
October 15, 2020 |
HETEROGENEOUS WET SYNTHESIS PROCESS FOR PREPARATION OF HIGH PURITY
TUNGSTEN PENTAHALIDE
Abstract
Synthesis of tungsten pentahalide compositions having low
impurity profiles are disclosed. The specific impurity profile
permits deposition of high purity tungsten-containing films using
vapor deposition processes or other semiconductor manufacturing
processes without introduction of performance-impacting
contaminants.
Inventors: |
LIU; Yumin; (San Jose,
CA) ; LI; Feng; (San Jose, CA) ; WAN;
Zhiwen; (Plano, TX) ; FAFARD; Claudia;
(Newark, DE) ; WIESE; Stefan; (San Jose, CA)
; HUSSON; Guillaume; (Newark, DE) ; NIKIFOROV;
Grigory; (Bridgewater, NJ) ; SUI; Bin;
(Houston, TX) ; GIRARD; Jean-Marc; (Versailles,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
L'Air Liquide, Societe Anonyme pour I'Etude et I'Exploitation des
Procedes Georges Claude
American Air Liquide, Inc. |
Paris
Fremont |
CA |
FR
US |
|
|
Family ID: |
1000004925948 |
Appl. No.: |
16/861275 |
Filed: |
April 29, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15966799 |
Apr 30, 2018 |
10669160 |
|
|
16861275 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01G 41/04 20130101 |
International
Class: |
C01G 41/04 20060101
C01G041/04 |
Claims
1. A method of synthesizing a WX.sub.5-containing composition,
wherein X is Cl or Br, the method comprising reacting approximately
1 molar equivalent of a tungsten hexahalide with approximately 0.4
to approximately 0.6 molar equivalents of a disilane in a water
reactive solvent to form a reaction mixture containing tungsten
pentahalide and a halosilane by-product.
2. The method of claim 1, wherein the tungsten pentahalide is
WCl.sub.5.
3. The method of claim 1, wherein the disilane has the formula
Si.sub.2R.sub.6, with each R independently being H, a C1-C4
hydrocarbyl group, or a halide.
4. The method of claim 3, wherein the disilane is
Si.sub.2Me.sub.6.
5. The method of claim 1, further comprising adding the tungsten
hexahalide to the water reactive solvent, wherein the water
reactive solvent comprises the halosilane by-product, to form a
suspension prior to the reacting step.
6. The method of claim 5, wherein the reacting step occurs when the
disilane is added to the suspension.
7. The method of claim 1, further comprising isolating the tungsten
pentahalide from the reaction mixture by evaporating the halosilane
by-product to produce an isolated WX.sub.5-containing
composition.
8. The method of claim 7, wherein the isolated WX.sub.5-containing
composition comprises between approximately 95% w/w WCl.sub.5 and
approximately 100% WCl.sub.5.
9. The method of claim 7, further comprising sublimating the
isolated WX.sub.5-containing composition to produce the
WX.sub.5-containing composition.
10. The method of claim 9, wherein the WX.sub.5-containing
composition comprising between approximately 0% to approximately
0.00002% by weight (0-200 ppb) of each of Al, Ti, V, Cr, Fe, Ni,
Cu, and Mo.
11. The method of claim 1, further comprising isolating the
tungsten pentahalide from the reaction mixture by filtration to
produce an isolated WX.sub.5-containing composition.
12. The method of claim 11, wherein the isolated
WX.sub.5-containing composition comprises between approximately 95%
w/w WCl.sub.5 and approximately 100% WCl.sub.5.
13. The method of claim 11, further comprising sublimating the
isolated WX.sub.5-containing composition to produce the
WX.sub.5-containing composition.
14. The method of claim 13, wherein the WX.sub.5-containing
composition comprising between approximately 0% to approximately
0.00002% by weight (0-200 ppb) of each of Al, Ti, V, Cr, Fe, Ni,
Cu, and Mo.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/966,799, filed Apr. 30, 2018, the entire
contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] Synthesis of tungsten pentahalide compositions having low
impurity profiles are disclosed. The specific impurity profile
permits deposition of high purity tungsten-containing films using
vapor deposition processes or other semiconductor manufacturing
processes without introduction of performance-impacting
contaminants.
BACKGROUND
[0003] Tungsten pentachloride is a precursor used in semiconductor
processing for deposition of Tungsten containing films or etching
processes. Tungsten (W) metal is used as plugs to connect M1 to
copper interconnects of the FEOL and BEOL in logic and memory
applications. See, e.g., US2009/0014879 to Park et al. Tungsten (W)
or tungsten silicide (WSi.sub.2) may also serve as a metal gate
deposited on Ti. See, e.g., US2014/0120723 to Fu et al. WCl.sub.5
has also been used to selectively etch substrates, such as metals,
metal nitrides, and metal oxides. See, e.g., U.S. Pat. No.
9,449,843 to Korolik et al. and U.S. Pat. No. 9,595,466 to Fu et
al.
[0004] Traven et al. disclose reactions of polysilanes and their
Group IVB analogs with tungsten hexachloride. Izvestiya Akademii
Nauk SSSR, Seriya Khimicheskaya (1975) 7, p. 1681.
[0005] Thorn-Csanyi et al. disclose reaction between WCl.sub.6 and
olefins to show that the reduction of WCl.sub.6 with olefins is
applicable to the preparation of WCl.sub.5. J. Molecular Catalysis,
1991, 65, 261-67.
[0006] WCl.sub.6 was reduced photolytically neat with
tetrachloroethylene to produce hexachloroethane and WCl.sub.5.
Inorganic Chemistry, 1968, 7, 6, 1227-1229.
[0007] A need remains for inexpensive and commercially viable
synthesis methods to produce tungsten halides having purity
suitable for use in the semiconductor industry.
SUMMARY
[0008] Methods for synthesizing WX.sub.5-containing compositions
are disclosed, wherein X is Cl or Br. Tungsten hexahalide is
reacted with an olefin in an aliphatic halohydrocarbon solvent to
form a reaction mixture. The WCl.sub.5-containing composition is
isolated from the reaction mixture. The disclosed methods may
include one or more of the following aspects: [0009] tungsten
hexahalide being WCl.sub.6; [0010] tungsten hexahalide being
WBr.sub.6; [0011] tungsten pentahalide being WCl.sub.5; [0012]
tungsten pentahalide being WBr.sub.5; [0013] reacting the tungsten
hexahalide with the olefin at a temperature ranging from
approximately 10.degree. C. to approximately 70.degree. C.; [0014]
reacting the tungsten hexahalide with the olefin at a temperature
ranging from approximately 10.degree. C. to approximately
28.degree. C.; [0015] reacting the tungsten hexahalide with the
olefin at a temperature ranging from approximately 15.degree. C. to
approximately 28.degree. C.; [0016] maintaining a reaction
temperature ranging from approximately 10.degree. C. to
approximately 70.degree. C.; [0017] maintaining a reaction
temperature ranging from approximately 10.degree. C. to
approximately 28.degree. C.; [0018] maintaining a reaction
temperature ranging from approximately 15.degree. C. to
approximately 28.degree. C.; [0019] stirring the reaction mixture
at a speed sufficient to maintain any solid reactant or product in
suspension; [0020] stirring the reaction mixture for approximately
10 min to approximately 48 hours prior to the isolation step;
[0021] stirring the reaction mixture for approximately 3 hours to
approximately 18 hours prior to the isolation step; [0022]
isolating the tungsten pentahalide from the reaction mixture by
evaporating the aliphatic halohydrocarbon solvent to produce an
isolated WX.sub.5-containing composition; [0023] isolating the
tungsten pentahalide from the reaction mixture by filtration to
produce a filtered tungsten pentahalide to produce an isolated
WX.sub.5-containing composition; [0024] rinsing the isolated
WX.sub.5-containing composition with a rinse solvent to produce
purified tungsten pentahalide; [0025] the aliphatic halohydrocarbon
solvent being the same as the rinse solvent; [0026] the aliphatic
halohydrocarbon solvent being different from the rinse solvent;
[0027] sublimating the purified tungsten pentahalide; [0028] adding
approximately 2 mL to approximately 20 mL of aliphatic
halohydrocarbon solvent per approximately 1 g of tungsten halide;
[0029] adding approximately 3 mL to approximately 10 mL of
aliphatic halohydrocarbon solvent per approximately 1 g of tungsten
halide; [0030] a molar ratio of the tungsten (VI) to the olefin
being between 0.5:1 and 2.5:1; [0031] a molar ratio of the tungsten
(VI) to the olefin being between 1:1 and 1.8:1; [0032] a molar
ratio of the Tungsten (VI) to the olefin being between 0.5:1 and
1.5:1; [0033] the olefin being selected from the group consisting
of cis/trans 2-pentene, 1-pentene, 1-hexene, 1,5-hexadiene,
2-methyl-1,3-butadiene, 2,3-dimethyl-2-butene,
3,3-dimethyl-1-butene, 4-methyl-1-pentene, cyclopentene, and
combinations thereof; [0034] the olefin having the formula
C.sub.nR.sub.2n, wherein each R is independently H or a C1-C4
hydrocarbyl group and n=4-11: [0035] the olefin being cis/trans
2-pentene; [0036] the olefin being 1-pentene; [0037] the olefin
being 1-hexene; [0038] the olefin being 2,3-dimethyl-2-butene;
[0039] the olefin being 3,3-dimethyl-1-butene; [0040] the olefin
being 4-methyl-1-pentene; [0041] the olefin having the formula
C.sub.nR.sub.2n-2, wherein each R is independently H or a C1-C4
hydrocarbyl group and n=4-11; [0042] the olefin being
1,5-hexadiene; [0043] the olefin being 2-methyl-1,3-butadiene;
[0044] the olefin having the formula cyclic C.sub.nR.sub.2n-2,
wherein each R is independently H or a C1-C4 hydrocarbyl group and
n=4-11; [0045] the olefin being cyclopentene; [0046] the olefin
having the formula cyclic C.sub.nR.sub.2n, wherein each R
independently is H or a C1-C4 hydrocarbyl group and n=4, 5, or
7-11; [0047] the olefin having the formula cyclic C.sub.nR.sub.2n,
wherein each R is independently H or a C1-C4 hydrocarbyl group and
n=4-11; [0048] the aliphatic halohydrocarbon solvent being selected
from the group consisting of dichloromethane, 1,2-dichloroethane,
trichlorofluoromethane, 1,1-dichloro-1-fluoroethane,
1-chloropropane, 1-chlorobutane, and combinations thereof; [0049]
the aliphatic halohydrocarbon solvent being selected from the group
consisting of 1-chlorobutane, dichloromethane, chloroform, and
combinations thereof; [0050] the aliphatic halohydrocarbon solvent
being 1-chlorobutane or dichloromethane; [0051] the rinse solvent
being selected from the group consisting of hydrocarbons,
halo-hydrocarbons, and halocarbons; [0052] the rinse solvent being
selected from the group consisting of toluene, heptane, pentane,
ethylbenzene, dichloroxylenes, 1-chlorobutane, dichloromethane,
chloroform, and dichlorobenzene; [0053] the rinse solvent being
selected from halo-hydrocarbons or halocarbons; [0054] the rinse
solvent being selected from the group consisting of
dichloroxylenes, 1-chlorobutane, dichloromethane, chloroform, and
dichlorobenzene; [0055] purifying the isolated Tungsten (V) halide
by fractional sublimation; and [0056] the purified WX.sub.5 having
a purity ranging from approximately 99% mol/mol to approximately
100% mol/mol.
[0057] Alternatively, the WX.sub.5-containing compositions may be
synthesized by reaction of tungsten hexahalide with a disilane or
polysilane to form a reaction mixture containing tungsten
pentahalide and a halosilane by-product. The WX.sub.5-containing
composition is isolated from the reaction mixture. The disclosed
methods may include one or more of the following aspects: [0058]
tungsten hexahalide being WCl.sub.6; [0059] tungsten hexahalide
being WBr.sub.6; [0060] tungsten pentahalide being WCl.sub.5;
[0061] tungsten pentahalide being WBr.sub.5; [0062] the disilane
having the formula Si.sub.2R.sub.6, with each R independently being
H, a C1-C4 hydrocarbyl group, or a halide; [0063] no more than 3 Rs
being a halide; [0064] the disilane having the formula
Si.sub.2R.sub.6, with each R independently being H, a C1-C4
hydrocarbyl group, or a halide, provided that no more than 3 R=a
halide; [0065] R being H or an alkyl group; [0066] the disilane
having the formula Si.sub.2Me.sub.6; [0067] the disilane having the
formula Si.sub.2iPr.sub.6; [0068] the disilane having the formula
Si.sub.2HMe.sub.5; [0069] the disilane having the formula
Si.sub.2H.sub.2Me.sub.4; [0070] the disilane having the formula
Si.sub.2H.sub.3Me.sub.3; [0071] the disilane having the formula
Si.sub.2H.sub.4Me.sub.2; [0072] the disilane having the formula
Si.sub.2Me.sub.5Cl; [0073] the disilane having the formula
Si.sub.2Me.sub.5Br; [0074] the disilane having the formula
Si.sub.2HMe.sub.4C (Me.sub.2HSi--SiMe.sub.2Cl); [0075] the disilane
having the formula Si.sub.2HMe.sub.4Br (Me.sub.2HSi--SiMe.sub.2Br);
[0076] the disilane having the formula
Si.sub.2Me.sub.4(CH.sub.2)Cl; [0077] the disilane having the
formula Si.sub.2H.sub.6; [0078] the disilane having the formula
Si.sub.2Cl.sub.2Me.sub.4; [0079] the disilane having the formula
Si.sub.2Br.sub.2Me.sub.4; [0080] the disilane having the formula
Si.sub.2Cl.sub.3Me.sub.3; [0081] the disilane having the formula
Si.sub.2Br.sub.3Me.sub.3; [0082] the disilane having the formula
Si.sub.2Et.sub.6; [0083] the disilane having the formula
Si.sub.2MeEt.sub.5; [0084] the disilane having the formula
Si.sub.2Me.sub.5Et; [0085] the disilane having the formula
Si.sub.2H.sub.2Me.sub.2Et.sub.2 (Me.sub.2HSi--SiHEt.sub.2); [0086]
the disilane having the formula Si.sub.2H.sub.2Me.sub.3.sup.iPr
(Me.sub.2HSi--SiHMe.sup.iPr); [0087] the disilane having the
formula Si.sub.2HMe.sub.4.sup.iPr
(Me.sub.2HSi--SiMe.sub.2.sup.iPr); [0088] the disilane having the
formula Si.sub.2Me.sub.5.sup.iPr; [0089] the disilane having the
formula Si.sub.2H.sub.2Me.sub.2.sup.iPr.sub.2; [0090] the disilane
having the formula Si.sub.2Me.sub.3.sup.iPr.sub.2; [0091] the
disilane having the formula Si.sub.2Me.sub.4.sup.iPr.sub.3; [0092]
the disilane having the formula Si.sub.2HMe.sub.2.sup.iPr.sub.3
(Me.sub.2HSi--SiiPr.sub.3); [0093] the disilane having the formula
Si.sub.2H.sub.2.sup.iPr.sub.4
(.sup.iPr.sub.2HSi--SiH.sup.iPr.sub.2); [0094] the disilane having
the formula Si.sub.2HMeEt.sup.iPr.sub.3
(MeEtHSi--Si.sup.iPr.sub.3); [0095] the disilane having the formula
Si.sub.2H.sub.2Me.sub.2Pr.sub.2; [0096] the polysilane having the
formula Si.sub.nR.sub.2n+2, with each R independently being H, a
C1-C4 hydrocarbyl group, or a halide and n=3-8; [0097] R being H or
an alkyl group; [0098] the polysilane containing no more than n+1
halides; [0099] the polysilane having the formula Si.sub.3Me.sub.8
(Me.sub.3Si-Me.sub.2Si--SiMe.sub.3); [0100] the polysilane having
the formula Si.sub.3H.sub.2Me.sub.6
(Me.sub.2HSi-Me.sub.2Si--SiHMe.sub.2;
Me.sub.3Si-Me.sub.2Si--SiH.sub.2Me); [0101] the polysilane having
the formula Si.sub.3H.sub.3Me.sub.5
(Me.sub.3Si-Me.sub.2Si--SiH.sub.3); [0102] the polysilane having
the formula Si.sub.3H.sub.3Me.sub.4C
(ClMe.sub.2Si-Me.sub.2Si--SiH.sub.3); [0103] the polysilane having
the formula Si.sub.4Me.sub.10
(Me.sub.3Si-Me.sub.2Si--SiMe.sub.2-SiMe.sub.3); [0104] the
polysilane having the formula Si.sub.4H.sub.6Me.sub.10
(H.sub.3Si-Me.sub.2Si--SiMe.sub.2-SiH.sub.3); [0105] the polysilane
having the formula Si.sub.5Me.sub.12; [0106] the polysilane having
the formula Si.sub.5H.sub.6Me.sub.6; [0107] the polysilane being a
cyclosilane having the formula Si.sub.nR.sub.2n (n=3-8); [0108] the
cyclosilane having the formula
Me.sub.2Si(CR'.sub.2).sub.nSiMe.sub.2 (R'=H or Me; n=1-4); [0109]
the cyclosilane having the formula Me.sub.2Si(CH.sub.2)SiMe.sub.2
(1,1,2,2-tetramethyl-disilacyclopropane); [0110] the cyclosilane
having the formula Si.sub.3H.sub.2Me.sub.4
(1,1,2,2-tetramethyl-cyclotrisilane); [0111] the cyclosilane having
the formula Si.sub.6Me.sub.12 (dodecamethylcyclohexasilane); [0112]
the halosilane by-product being R.sub.3SiX, wherein each R is
independently H, a C1-C4 hydrocarbyl group, or a halide, and X is
from the WX.sub.6 reactant; [0113] the halosilane by-product from
the disilane or linear polysilane reactant being R.sub.3Cl, wherein
each R is independently H, a C1-C4 hydrocarbyl group, or a halide,
and X is from the WX.sub.6 reactant; [0114] the halosilane
by-product being trimethyl silyl chloride (Me.sub.3SiCl); [0115]
the halosilane by-product being trimethyl silyl bromide
(Me.sub.3SiBr); [0116] the halosilane by-product being triethyl
silyl chloride (Et.sub.3SiCl); [0117] the halosilane by-product
being triethyl silyl bromide (Et.sub.3SiBr); [0118] the halosilane
by-product being tri-isopropyl silyl chloride (iPr.sub.3SiCl);
[0119] the halosilane by-product being tri-isopropyl silyl bromide
(iPr.sub.3SiBr); [0120] the halosilane by-product being dimethyl
silyl chloride (Me.sub.2SiHCl); [0121] the halosilane by-product
being dimethyl silyl bromide (Me.sub.2SiHBr); [0122] the halosilane
by-product being R.sub.2SiX.sub.2, wherein each R is independently
H, a C1-C4 hydrocarbyl group, or a halide, and X is from the
WX.sub.6 reactant; [0123] the halosilane by-product from linear or
cyclic polysilanes being R.sub.2SiX.sub.2, wherein each R is
independently H, a C1-C4 hydrocarbyl group, or a halide, and X is
from the WX.sub.6 reactant; [0124] the halosilane by-product being
dimethyl silyl dichloride (Me.sub.2SiCl.sub.2); [0125] the
halosilane by-product being dimethyl silyl dibromide
(Me.sub.2SiBr.sub.2); [0126] the halosilane by-product being
diethyl silyl dichloride (Et.sub.2SiCl.sub.2); [0127] the
halosilane by-product being diethyl silyl dibromide
(Et.sub.2SiBr.sub.2); [0128] the halosilane by-product being
di-isopropyl silyl dichloride (iPr.sub.2SiCl.sub.2); [0129] the
halosilane by-product being di-isopropyl silyl dibromide
(iPr.sub.2SiBr.sub.2); [0130] the halosilane by-product being
methyl silyl dichloride (Me.sub.2SiHCl.sub.2); [0131] the
halosilane by-product being methyl silyl dibromide
(Me.sub.2SiHBr.sub.2); [0132] the halosilane by-product being a
combination of R.sub.3X and R.sub.2SiX.sub.2, wherein each R is
independently H, a C1-C4 hydrocarbyl group, or a halide, and X is
from the WX.sub.6 reactant; [0133] the reaction mixture consisting
essentially of tungsten pentahalide and a halosilane by-product;
[0134] the reaction mixture consisting of tungsten pentahalide and
a halosilane by-product; [0135] the tungsten hexahalide and
disilane or polysilane being reacted in a solvent; [0136] the
tungsten hexahalide and disilane or polysilane being reacted
without a solvent; [0137] suspending the tungsten hexahalide in a
solvent prior to reaction with the disilane or polysilane; [0138]
dissolving the disilane or polysilane in a solvent prior to
reaction with tungsten hexahalide; [0139] the solvent being the
halosilane by-product; [0140] reacting the tungsten hexahalide with
the disilane or polysilane at a temperature ranging from
approximately 10.degree. C. to approximately the boiling point of
the disilane or polysilane and/or solvent; [0141] reacting the
tungsten hexahalide with the disilane or polysilane at a
temperature ranging from approximately 10.degree. C. to
approximately 50.degree. C.; [0142] reacting the tungsten
hexahalide with the disilane or polysilane at a temperature ranging
from approximately 10.degree. C. to approximately 40.degree. C.;
[0143] reacting the tungsten hexahalide with the disilane or
polysilane at a temperature ranging from approximately 10.degree.
C. to approximately 28.degree. C.; [0144] reacting the tungsten
hexahalide with the disilane or polysilane at a temperature ranging
from approximately 15.degree. C. to approximately 28.degree. C.;
[0145] maintaining a reaction temperature ranging from
approximately 10.degree. C. to approximately 50.degree. C.; [0146]
maintaining a reaction temperature ranging from approximately
10.degree. C. to approximately 40.degree. C.; [0147] maintaining a
reaction temperature ranging from approximately 10.degree. C. to
approximately 28.degree. C.; [0148] maintaining a reaction
temperature ranging from approximately 15.degree. C. to
approximately 28.degree. C.; [0149] stirring the reaction mixture
at a speed sufficient to maintain any solid reactant or product in
suspension; [0150] stirring the reaction mixture for approximately
10 min to approximately 48 hours prior to the isolation step;
[0151] stirring the reaction mixture for approximately 1 hours to
approximately 18 hours prior to the isolation step; [0152] stirring
the reaction mixture for approximately 3 hours to approximately 8
hours prior to the isolation step; [0153] isolating the
WX.sub.5-containing composition from the reaction mixture by
evaporating the halosilane by-product to produce an isolated
WX.sub.5-containing composition; [0154] isolating the
WX.sub.5-containing composition from the reaction mixture by
evaporating the halosilane by-product and solvent to produce an
isolated WX.sub.5-containing composition; [0155] isolating the
WX.sub.5-containing composition from the reaction mixture by
filtration to produce a filtered tungsten pentahalide to produce an
isolated WX.sub.5-containing composition; [0156] the isolated
WX.sub.5-containing composition comprising approximately 85% w/w to
approximately 100% w/w WX.sub.5; [0157] the isolated
WX.sub.5-containing composition comprising approximately 90% w/w to
approximately 100% w/w WX.sub.5; [0158] the isolated
WX.sub.5-containing composition comprising approximately 95% w/w to
approximately 100% w/w WX.sub.5; [0159] rinsing the isolated
WX.sub.5-containing composition with a rinse solvent to produce
purified tungsten pentahalide; [0160] the halosilane by-product
being the same as the rinse solvent; [0161] the halosilane
by-product being different from the rinse solvent; [0162]
sublimating the isolated WX.sub.5-containing composition; [0163] a
molar ratio of the disilane to the tungsten (VI) halide being
between 0.4:1 and 0.6:1; [0164] a molar ratio of the polysilane
having the formula Si.sub.nR.sub.2n+2 to the tungsten (VI) halide
being between approximately 2/(5n-5):1 and approximately
3/(5n-5):1.
[0165] Also disclosed are the WX.sub.5-containing compositions
synthesized by the methods disclosed above. The disclosed
WX.sub.5-containing compositions include on or more of the
following aspects: [0166] the WX.sub.5-containing composition
comprising between approximately 85% w/w and approximately 100% w/w
WX.sub.5; [0167] the WX.sub.5-containing composition comprising
between approximately 90% w/w and approximately 100% w/w WX.sub.5;
[0168] the WX.sub.5-containing composition comprising between
approximately 95% w/w and approximately 100% w/w WX.sub.5; [0169]
the WCl.sub.5-containing composition comprising between
approximately 85% w/w and approximately 100% w/w WCl.sub.5; [0170]
the WCl.sub.5-containing composition comprising between
approximately 90% w/w and approximately 100% w/w WCl.sub.5; [0171]
the WCl.sub.5-containing composition comprising between
approximately 95% w/w and approximately 100% w/w WCl.sub.5; [0172]
the WBr.sub.5-containing composition comprising between
approximately 85% w/w and approximately 100% w/w WBr.sub.5; [0173]
the WBr.sub.5-containing composition comprising between
approximately 90% w/w and approximately 100% w/w WBr.sub.5; [0174]
the WBr.sub.5-containing composition comprising between
approximately 95% w/w and approximately 100% w/w WBr.sub.5; [0175]
an Al concentration ranging from approximately 0% to approximately
0.0001% by weight (0-1000 ppb); [0176] an Al concentration ranging
from approximately 0% to approximately 0.00005% by weight (0-500
ppb); [0177] an Al concentration ranging from approximately 0% to
approximately 0.00002% by weight (0-200 ppb); [0178] a Ti
concentration ranging from approximately 0% to approximately
0.00005% by weight (0-500 ppb); [0179] a Ti concentration ranging
from approximately 0% to approximately 0.000015% by weight (0-150
ppb); [0180] a Ti concentration ranging from approximately 0% to
approximately 0.000005% (0-50 ppb); [0181] a V concentration
ranging from approximately 0% to approximately 0.00005% by weight
(0-500 ppb); [0182] a V concentration ranging from approximately 0%
to approximately 0.00002% (0-200 ppb), [0183] a V concentration
ranging from approximately 0% to approximately 0.000005% (0-50
ppb),) [0184] a Cr concentration ranging from approximately 0% to
approximately 0.0001% by weight; (0-1000 ppb); [0185] a Cr
concentration ranging from approximately 0% to approximately
0.00005% by weight (0-500 ppb); [0186] a Cr concentration ranging
from approximately 0% to approximately 0.00001% by weight (0-100
ppb); [0187] a Fe concentration ranging from approximately 0% to
approximately 0.0001% by weight; (0-1000 ppb); [0188] a Fe
concentration ranging from approximately 0% to approximately
0.00005% (0-500 ppb); [0189] a Fe concentration ranging from
approximately 0% to approximately 0.00002% by weight (0-200 ppb);
[0190] a Ni concentration ranging from approximately 0% to
approximately 0.0001% by weight (0-1000 ppb); [0191] a Ni
concentration ranging from approximately 0% to approximately
0.00005% by weight (0-500 ppb); [0192] a Ni concentration ranging
from approximately 0% to approximately 0.00001% by weight (0-100
ppb); [0193] a Cu concentration ranging from approximately 0% to
approximately 0.00005% by weight (0-500 ppb); [0194] a Cu
concentration ranging from approximately 0% to approximately
0.000015% by weight (0-150 ppb); [0195] a Cu concentration ranging
from approximately 0% to approximately 0.000005% by weight (0-50
ppb); [0196] a Mo concentration ranging from approximately 0% to
approximately 0.0002% by weight; (0-2000 ppb); [0197] a Mo
concentration ranging from approximately 0% to approximately
0.00005% by weight (0-500 ppb); [0198] a Mo concentration ranging
from approximately 0% to approximately 0.00002% by weight (0-200
ppb).
Notation and Nomenclature
[0199] Certain abbreviations, symbols, and terms are used
throughout the following description and claims, and include:
[0200] As used herein, the indefinite article "a" or "an" means one
or more.
[0201] As used herein, the terms "approximately" or "about"
mean.+-.10% of the value stated.
[0202] As used herein, the term "comprising" is inclusive or
open-ended and does not exclude additional, unrecited materials or
method steps; the term "consisting essentially of" limits the scope
of a claim to the specified materials or steps and additional
materials or steps that do not materially affect the basic and
novel characteristics of the claimed invention; and the term
"consisting of" excludes any additional materials or method steps
not specified in the claim.
[0203] As used herein, the term "independently" when used in the
context of describing R groups should be understood to denote that
the subject R group is not only independently selected relative to
other R groups bearing the same or different subscripts or
superscripts, but is also independently selected relative to any
additional species of that same R group. For example in the formula
MR.sup.1.sub.x (NR.sup.2R.sup.3).sub.(4-x), where x is 2 or 3, the
two or three R groups may, but need not be identical to each other
or to R.sup.2 or to R.sup.3. Further, it should be understood that
unless specifically stated otherwise, values of R groups are
independent of each other when used in different formulas.
[0204] As used herein, the term "hydrocarbyl group" refers to a
functional group containing carbon and hydrogen; the term "alkyl
group" refers to saturated functional groups containing exclusively
carbon and hydrogen atoms. The hydrocarbyl group may be saturated
or unsaturated. Either term refers to linear, branched, or cyclic
groups. Examples of linear alkyl groups include without limitation,
methyl groups, ethyl groups, propyl groups, butyl groups, etc.
Examples of branched alkyls groups include without limitation,
t-butyl. Examples of cyclic alkyl groups include without
limitation, cyclopropyl groups, cyclopentyl groups, cyclohexyl
groups, etc.
[0205] As used herein, the abbreviation "Me" refers to a methyl
group; the abbreviation "Et" refers to an ethyl group; the
abbreviation "Pr" refers to a propyl group; the abbreviation "nPr"
refers to a "normal" or linear propyl group; the abbreviation "iPr"
refers to an isopropyl group; the abbreviation "Bu" refers to a
butyl group; the abbreviation "nBu" refers to a "normal" or linear
butyl group; the abbreviation "tBu" refers to a tert-butyl group,
also known as 1,1-dimethylethyl; the abbreviation "sBu" refers to a
sec-butyl group, also known as 1-methylpropyl; the abbreviation
"iBu" refers to an iso-butyl group, also known as 2-methylpropyl;
the term "halide" refers to the halogen anions F.sup.-, Cl.sup.-,
Br.sup.-, and I.sup.-; and the abbreviation "TMS" refers to
trimethylsilyl or --SiMe.sub.3.
[0206] As used herein, the abbreviation "RT" means room temperature
or a temperature ranging from approximately 18.degree. C. to
approximately 25.degree. C.
[0207] As used herein, the term "olefin" means an unsaturated
hydrocarbon containing at least one carbon-carbon double bond.
[0208] As used herein, the term "aliphatic halohydrocarbon solvent"
means that the halogen-containing hydrocarbon solvent is not an
aromatic compound, such as benzene or toluene. In other words, the
disclosed solvents do not include any aromatic compounds, which are
cyclic, planar molecules with a ring of resonance bonds.
[0209] As used herein, the term "anhydrous" means containing
between approximately zero ppmv and approximately 100 ppmv moisture
and preferably between approximately zero ppmv and approximately 10
ppmv moisture.
[0210] As used herein, any reference to WX.sub.5 includes the
monomeric WX.sub.5, the dimeric W.sub.2X.sub.10, and combinations
thereof.
[0211] Throughout the specification and claims, the halogen atoms X
on the tungsten hexahalide reactant, tungsten pentahalide reaction
product, halosilane by-product, and solvent must be the same (e.g.,
WCl.sub.6+Si.sub.2Me.sub.6.fwdarw.WCl.sub.5+SiMe.sub.3Cl;
WBr.sub.6+Si.sub.2Me.sub.6.fwdarw.WBr.sub.5+SiMe.sub.3Br).
[0212] The standard abbreviations of the elements from the periodic
table of elements are used herein. It should be understood that
elements may be referred to by these abbreviations (e.g., W refers
to tungsten, Mn refers to manganese, Si refers to silicon, C refers
to carbon, H refers to hydrogen, etc.).
[0213] Any and all ranges recited herein are inclusive of their
endpoints (i.e., x=1 to 4 or x ranges from 1 to 4 includes x=1,
x=4, and x=any number in between), irrespective of whether the term
"inclusively" is used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0214] For a further understanding of the nature and objects of the
present invention, reference should be made to the following
detailed description, taken in conjunction with the accompanying
drawing wherein:
[0215] FIG. 1 is a schematic diagram of an apparatus in which the
disclosed synthesis methods may be performed;
[0216] FIG. 2 is a ThermoGravimetric Analysis (TGA) plot
illustrating the percentage of weight loss upon temperature
increase of WCl.sub.4, WCl.sub.5, and a controlled mixture of the
two;
[0217] FIG. 3 is a ThermoGravimetric Analysis/Differential Thermal
Analysis (TGA/DTA) plot illustrating the percentage of weight loss
(TGA) or the differential temperature (DTA) upon temperature
increase of the WCl.sub.5 product of Example 1 before
sublimation;
[0218] FIG. 4 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the WCl.sub.5 product of Example 1 after
sublimation;
[0219] FIG. 5 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the WCl.sub.5 product of Example 4;
[0220] FIG. 6 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the WCl.sub.5 product of Example 5;
[0221] FIG. 7 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the product of Comparative Example 1;
and
[0222] FIG. 8 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the product of Comparative Example 2.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0223] Methods for preparing WX.sub.5-containing compositions at
high purity levels are disclosed. The disclosed heterogeneous wet
synthesis methods produce the WX.sub.5-containing composition from
tungsten (VI) halides. The disclosed methods produce products
having purities suitable for use in semiconductor processing. The
disclosed methods do not require complicated apparatus.
[0224] Both methods described herein minimize the formation of
over-reduced by-products, such as Tungsten (IV) halide (i.e.,
WX.sub.4). Additionally, both methods operate under atmospheric
pressure and at low temperatures. At these temperature and pressure
conditions, tungsten halides are at least partially present as
solids in the solvent and the reactions take place as a
heterogeneous mixture.
Olefin Reaction
[0225] Tungsten hexahalide (i.e., WX.sub.6) is added to a reactor.
WCl.sub.6 and WBr.sub.6 are commercially available. A solvent is
added to form a heterogeneous mixture at a temperature ranging from
approximately 10.degree. C. to approximately 70.degree. C. An
olefin is added to the mixture. The mixture is stirred to form a
stirred heterogeneous mixture at a speed sufficient to maintain any
solids in suspension. The WX.sub.5-containing composition is
isolated from the stirred mixture.
[0226] The reactions are described in the following equations:
2 WX.sub.6(s)+C.sub.nR.sub.2n(l).fwdarw.2 WX.sub.5
(s)+C.sub.nR.sub.2nX.sub.2 (l)
2 WX.sub.6 (s)+C.sub.nR.sub.2n-2 (l).fwdarw.2 WX.sub.5
(s)+C.sub.nR.sub.2n-2X.sub.2 (l)
2 WX.sub.6 (s)+C.sub.nR.sub.2n-2 cyclic (l).fwdarw.2 WX.sub.5
(s)+C.sub.nR.sub.2n-2X.sub.2 cyclic (l)
2 WX.sub.6 (s)+C.sub.nR.sub.2n-2 cyclic (l).fwdarw.2 WX.sub.5
(s)+C.sub.nR.sub.2n-4X.sub.2 cyclic (l)
2 WX.sub.6 (s)+C.sub.nR.sub.2n-6 cyclic (l).fwdarw.2 WX.sub.5
(s)+C.sub.nR.sub.2n-6X.sub.2 cyclic (l)
Wherein l=liquid; s=solid; X=Cl or Br; each R is independently H or
C1-C4 hydrocarbyl, preferably H or Me; and n=5-11, provided that
n.noteq.6 for cyclic C.sub.nR.sub.2n-4
[0227] The tungsten (VI) halide may be added to a reactor
containing the solvent or vice versa. In other words, the order of
addition is not important. The solvent may be added to a reactor
containing the tungsten (VI) halide to form a suspension at a
temperature ranging from approximately 10.degree. C. to
approximately 70.degree. C., preferably ranging from approximately
15.degree. C. to approximately 28.degree. C. The reactant, tungsten
(VI) halide, will remain at least partially solid, producing a
suspension in the solvent during the reaction. The pressure in the
reactor is preferably around atmospheric pressure (approximately 91
kPa to approximately 112 kPa). The ratio of solvent to tungsten
(VI) halide is chosen from the range of approximately 3 mL to
approximately 20 mL of solvent per approximately 1 g of tungsten
(VI) halide, preferably approximately 3 mL to approximately 10 mL
of solvent per approximately 1 g of tungsten (VI) halide.
[0228] As tungsten halides may degrade to tungsten oxyhalides,
other tungsten halides, and/or tungsten oxides, care must be taken
to ensure that the tungsten halide reactant has a purity ranging
from approximately 90% mol/mol to approximately 100% mol/mol.
Preferably, the tungsten halide has a purity ranging from
approximately 95% mol/mol to approximately 100% mol/mol, and more
preferably from approximately 99% mol/mol to approximately 100%
mol/mol. One of ordinary skill in the art will recognize that the
tungsten halide reactant purity may be determined at least by using
UV/VIS spectroscopy. See, e.g., Thom-Csanyi et al., Journal of
Molecular Catalysis 65 (1991) pp. 261-267. One of ordinary skill in
the art would also recognize that the tungsten (VI) halide may be
purified using sublimation, when necessary.
[0229] Tungsten halide reactants containing tungsten oxyhalides,
other tungsten halides, and/or tungsten oxides content lead to low
yields of Tungsten (V) halides. Therefore, the tungsten oxyhalides,
other tungsten halides, and tungsten oxides contents in the
tungsten (VI) halide reactant may range from approximately 0%
mol/mol to approximately 10% mol/mol, preferably from approximately
0% mol/mol to approximately 5% mol/mol, and more preferably from
approximately 0% mol/mol to approximately 1% mol/mol.
[0230] The solvent may be a hydrocarbon, halo-hydrocarbon,
halocarbon (acyclic or cyclic), or mixtures thereof. Preferably,
the anhydrous solvent is a halo-hydrocarbon or halocarbon.
Applicants believe that aliphatic halohydrocarbon solvents
facilitate formation of the desired tungsten pentahalide
product.
[0231] Furthermore, the solvent must be a liquid at the reaction
temperature and pressure. Therefore, the selected solvent remains a
liquid at temperatures ranging between 10.degree. C. and the
boiling point of the olefin at atmospheric pressure. The solvent
must also be dry (anhydrous) in order to prevent the formation of
oxygenated species, such as tungsten oxides or oxyhalides. One of
ordinary skill in the art would recognize the methods required to
prepare an anhydrous solvent. The solvent may contain between
approximately zero ppmv and approximately 100 ppmv moisture.
Preferably, the solvent contains between approximately zero ppmv
and approximately 10 ppmv moisture.
[0232] Exemplary solvents include dichloromethane, chloroform,
trichlorofluoromethane, Dichlorodifluoromethane,
1,2-dichloroethane, 1,1-dichloroethane, 1-chloro-2-fluoroethane,
1,1,1-trichloroethane, 1,1,2-trichloroethane,
2-chloro-1,1-difluoroethane, 1,1-dichloro-1-fluoroethane,
1,1-Dichloro-1,2-difluoroethane, 1,1-Dichloro-2,2-difluoroethane,
1,2-Dichloro-1,2-difluoroethane, 1,2-Dichloro-1,1-difluoroethane,
1,1,2-Trichloro-1-fluoroethane, 1,1,2-Trichloro-1,2-difluoroethane,
1,2-Dichlorotetrafluoroethane, 2-chloro-1,1,1-trifluoroethane,
1,1,2-Trichloro-2-fluoroethane, 1-chloro-1,1,2,2-tetrafluoroethane,
1,2,2-Trichloro-1,1-difluoroethane,
1,1,2,2-Tetrachlorofluoroethane,
1-Bromo-2-chloro-1,1,2-trifluoroethane,
2-Bromo-2-chloro-1,1,1-trifluoroethane,
1,1,1-Trichloro-2,2,2-trifluoroethane,
1,1,2-Trichloro-1,2,2-trifluoroethane,
Tetrachloro-1,2-difluoroethane, Tetrachloro-1,1-difluoroethane,
1-chloropropane, 2-chloropropane,
3,3-Dichloro-1,1,1,2,2-pentafluoropropane,
1,2-Dichloro-1,2,2,3,3-pentafluoropropane, 1-chlorobutane,
chloroform, 2-chlorobutane, 2-methylbutane, 2,2-dimethylbutane,
2,3-dimethylbutane, pentane, 2-methylpentane, 3-methylpentane,
2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane,
hexane, cyclohexane, octane, ethylbenzene, chlorobenzene, xylenes,
or combinations thereof. These solvents are commercially available
or may be synthesized by methods known in the art.
[0233] Preferably, the solvent is a low boiling point solvent
because it is easier to remove by vacuum at the end of the
synthesis process. The boiling point of the solvent is preferably
below the melting point of any of the reactants or products. For
example, the boiling point of the solvent is preferably below its
approximately 240.degree. C. melting point of tungsten
pentachloride for the synthesis of tungsten pentachloride, and more
preferably below 200.degree. C. Exemplary low boiling point
solvents include pentane, hexane, dichloromethane,
1,2-dichloroethane, trichlorofluoromethane,
1,1-dichloro-1-fluoroethane, 1,1,1-trichloro-2,2,2-trifluoroethane,
1,1,2-trichloro-1,2,2-trifluoroethane, and combinations thereof.
More preferably, the low boiling point solvent is an aliphatic
halohydrocarbon, such as dichloromethane, 1,2-dichloroethane,
trichlorofluoromethane, 1,1-dichloro-1-fluoroethane,
1,1,1-trichloro-2,2,2-trifluoroethane,
1,1,2-trichloro-1,2,2-trifluoroethane, and combinations
thereof.
[0234] An olefin having the formula C.sub.nR.sub.2n-2,
C.sub.nR.sub.2n-4, cyclic C.sub.nR.sub.2n-2, cyclic
C.sub.nR.sub.2n-4, cyclic C.sub.nR.sub.2n-6, wherein each R is
independently H or a C1-C4 hydrocarbyl group and n=4-11, provided
that n is not 6 for cyclic C.sub.nR.sub.2n-4, is added to the
reactor containing the tungsten (VI) halide/solvent suspension to
produce a mixture at a temperature ranging from approximately
10.degree. C. to approximately 70.degree. C., preferably ranging
from approximately 10.degree. C. to approximately 28.degree. C.,
and more preferably at approximately room temperature (i.e.,
approximately 20.degree. C. to approximately 27.degree. C.).
Preferably, the reaction is not or only slightly exothermic and
therefore the reaction temperature is maintained at or close to the
original addition temperature. The olefin may be added as a liquid
or gas. When the olefin is a gas, a solvent capable of dissolving
the gaseous olefin must be selected. Once again, the olefin should
be anhydrous and preferably contains between approximately zero
ppmv and approximately 100 ppmv moisture to prevent the formation
of oxygenated species, such as tungsten oxides or oxyhalides. The
pressure in the reactor preferably remains around atmospheric
pressure for safety and cost reasons. However, one of ordinary
skill in the art will recognize that the reaction may also be
performed in a pressure reactor without deviating from the
teachings herein.
[0235] Exemplary olefins having the formula C.sub.nR.sub.2n,
wherein each R is independently H or a C1-C4 hydrocarbyl group and
n=4-11, include 1-pentene, 2-methyl-1-butene, trans-2-pentene,
cis-2-pentene, 1-2-methyl-2-butene, 3,3-dimethyl-1-butene,
4-methyl-1-pentene, 3-methyl-1-pentene, 2,3-dimethyl-1-butene,
4-methyl-cis-2-pentene, 4-methyl-trans-2-pentene,
2-methyl-1-pentene, 1-hexene, 2-ethyl-1-butene, cis-3-hexene,
trans-3-hexene, 2-methyl-2-pentene, 3-methyl-trans-2-pentene,
trans-2-hexene, cis-2-hexene, 3-methyl-cis-2-pentene,
4,4,-dimethyl-1-pentene, 2,3-dimethyl-2-butene,
4,4-dimethyl-trans-2-pentene, 3,3-dimethyl-1-pentene,
2,3,3-trimethyl-1-butene, 4,4-dimethyl-cis-2-pentene,
3,4-dimethyl-1-pentene, 2,4-dimethyl-2-pentene, 3-methyl-1-hexene,
2,3-dimethyl-1-pentene, 3-ethyl-1-pentene, 5-methyl-1-hexene,
5-methyl-trans-2-hexene, 2-methyl-3-hexene, 4-methyl-1-hexene,
3,4-dimethyl-2-pentene, 4-methyl-cis-2-hexene,
4-methyl-trans-2-hexene, 2-ethyl-3-methyl-1-butene,
5-methyl-cis-2-hexene, 2-methyl-1-hexene, 3-methyl-trans-3-hexene,
1-heptene, 3-methyl-trans-2-hexene, 2-ethyl-1-pentene,
3-methyl-cis-3-hexene, 2-methyl-2-hexene, cis-3-heptene,
5-3-ethyl-2-pentene, 2,3-dimethyl-2-pentene, trans-2-heptene,
cis-2-heptene, 2,2-dimethyl-trans-3-hexene,
2,4,4-trimethyl-1-pentene, 2,5-dimethyl-3-hexene,
5,5-dimethyl-1-hexene, 2-isopropyl-3-methyl-1-butene,
3,4,4-trimethyl-1-pentene, 3,5-dimethyl-1-hexene,
3,3-dimethyl-1-hexene, 5,5-dimethyl-trans-2-hexene,
2,4,4-trimethyl-2-pentene, 3,3,4-trimethyl-1-pentene,
2,2-dimethyl-cis-3-hexene, 4,4-dimethyl-2-hexene,
5,5-dimethyl-cis-2-hexene, 4,4-dimethyl-1-hexene,
3-ethyl-4-methyl-1-pentene, 2,4-dimethyl-trans-3-hexene,
2,3,4-trimethyl-1-pentene, 2,3,3-trimethyl-1-pentene,
4,5-dimethyl-1-hexene, 2,4-dimethyl-cis-3-hexene,
3,3-dimethyl-2-ethyl-1-butene, 3-ethyl-2-methyl-1-pentene,
4,5-dimethyl-2-hexene, 2-ethyl-4-methyl-1-pentene,
3-ethyl-1-hexene, 2,3-dimethyl-1-hexene, 2,4-dimethyl-4-hexene,
3-methyl-1-heptene, 2,4-dimethyl-1-hexene, 3-methyl-1-heptene,
2,4-dimethyl-1-hexene, 2,5-dimethyl-1-hexene,
3-ethyl-3-methyl-1-pentene, 3,4-dimethyl-1-hexene,
3,4,4,-trimethyl-2-pentene, 3,5-dimethyl-2-hexene,
2-methyl-3-heptene, 5-methyl-3-heptene, 2,5-dimethyl-2-hexene,
2-ethyl-3-methyl-1-pentene, 4-methyl-1-heptene, 6-methyl-3-heptene,
4-ethyl-2-hexene, 2-isopropyl-1-pentene, 5-methyl-1-heptene,
4-methyl-2-heptene, 2,3-dimethyl-3-hexene, 4-methyl-2-octene,
4-ethyl-4-methyl-trans-2-pentene, 3-ethyl-4-methyl-cis-2-pentene,
3,4-dimethyl-2-hexene, 3-ethyl-3-hexene, 2,3,4-trimethyl-2-pentene,
6-methyl-2-heptene, 2-n-propyl-1-pentene, 5-methyl-2-heptene,
2-methyl-1-heptene, 2-ethyl-1-hexene, 4-methyl-3-heptene,
3-ethyl-2-hexene, 3-methyl-3-heptene, 1-octene, trans-4-octene,
3-methyl-2-heptene, trans-4-octene, 3-methyl-2-heptene,
cis-4-octene, 2,3-dimethyl-2-hexene, 3,4-dimethyl-trans-3-hexene,
6-methyl-1-heptene, cis-3-octene, trans-3-octene,
2-methyl-2-heptene, trans-2-octene, cis-2-octene,
2,6-dimethyl-2-heptene, 2-methyl-4-octene, 7-methyl-3-octene,
2-methyl-2-octene, 4-nonene, 1-nonene, 2-nonene, 5-decene,
1-decene, 4-decene, 2-undecene, 5-undecene, 1-undecene, 1-dodecene,
and combinations thereof. These olefins are either commercially
available or may be synthesized by methods known in the art. One of
ordinary skill in the art will further recognize that aromatics,
terpenes, ethylidene, isopropenyl, and bicyclics may also be used
as the olefin without departing from the teachings herein.
[0236] Exemplary olefins having the formula C.sub.nR.sub.2n-2,
wherein each R is independently H or a C1-C4 hydrocarbyl group and
n=4-11, include 1,4-pentadiene, 2-methyl-1,3-butadiene,
3-methyl-1-2-butadiene, 1,3-pentadiene (piperylene),
1-trans-3-pentadiene, 1-cis-3-pentadiene, 1,2-pentadiene,
2,3-pentadiene, 3-methyl-1,4-pentadiene, 2-methyl-1,4-pentadiene,
1,5-hexadiene, trans-1,3-hexadiene, 2,3-hexadiene,
2,3-dimethyl-1,3-butadiene, 4-methyl-1,2-pentadiene,
2-methyl-2,3-pentadiene, 1,4-hexadiene, 2-ethyl-1,3-butadiene,
1,2-hexadiene, 4-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,
3-methyl-1,2-pentadiene, 2,4-hexadiene, 2-methyl-1,5-hexadiene,
4,4-dimethyl-1,2-pentadiene, 2,4-dimethyl-2,3-pentadiene,
5-methyl-1,4-hexadiene, 2-methyl-1,5-hexadiene,
2,4-dimethyl-1,3-pentadiene, methyl-1,2-hexadiene, 1,4-heptadiene,
3,3-dimethyl-1,5-hexadiene, 3,4-dimethyl-1,5-hexadiene,
1,2-heptadiene, 2-methyl-2,4-hexadiene, 3-methyl-2,4-hexadiene,
2,4-heptadiene, 4-methyl-1,3-hexadiene, 3-methyl-1,5-heptadiene,
2,4-dimethyl-2,4-hexadiene, 6-methyl-2,4-heptadiene,
6-methyl-1,3-heptadiene, 2,5-dimethyl-1,3-hexadiene,
2,5-dimethyl-1,5-hexadiene, 2-methyl-1,3-heptadiene,
4-methyl-2,4-heptadiene, 3-methyl-2,4-heptadiene,
3,5-dimethyl-2,4-heptadiene, 2,4-octadiene,
2,5-dimethyl-2,5-hexadiene, 2,6-dimethyl-2,4-heptadiene,
2,6-dimethyl-1,3-heptadiene, 2,6-dimethyl-1,5-heptadiene,
1,8-nonadiene, 3,6-dimethyl-2,4-heptadiene,
2,6-dimethyl-2,5-heptadiene, 2,7-nonadiene,
4,4-dimethyl-1,7-octadiene, 4,5-dimethyl-2,6-octadiene,
3,6-dimethyl-2,6-octadiene, 2,6-dimethyl-2,7-octadiene,
2,4-dimethyl-2,4-octadiene, 2,7-dimethyl-2,6-octadiene,
3,7-dimethyl-2,4-octadiene, 2,6-dimethyl-2,6-octadiene, and
combinations thereof. These olefins are either commercially
available or may be synthesized by methods known in the art.
[0237] Exemplary olefins having the formula C.sub.nR.sub.2n4,
wherein each R is independently H or a C1-C4 hydrocarbyl group and
n=4-11, include trans-1,3,5-hexatriene, cis-1,3,5-hexatriene, and
combinations thereof. These olefins are either commercially
available or may be synthesized by methods known in the art.
[0238] Exemplary olefins having the formula cyclic
C.sub.nR.sub.2n-2, wherein each R is independently H or a C1-C4
hydrocarbyl group and n=4-11, include 3-methylcyclobutene,
cyclopentene, methylcyclobutene, 3-methylcyclopentene,
4-methylcyclopentene, 1-methylcyclopentene, cyclohexene,
3,3-dimethylcyclopentene, 1,3-dimethylcyclopentene,
1,4-dimethylcyclopentene, 3-ethylcyclopentene, 4-methylcyclohexene,
3-methylcyclohexene, 1,2-dimethylcyclopentene, 4-ethylcyclopentene,
1-ethylcyclopentene, 1,5,5-trimethylcyclopentene,
1-methylcyclohexene, cycloheptene, 4,4-dimethylcyclohexene,
3,3-dimethylcyclohexene, 1,2,3-trimethylcyclopentene,
1,4-dimethylcyclohexene, 1,5-dimethylcyclohexene,
4-vinylcyclohexene, 4-ethylcyclohexene, 4-ethylcyclohexene,
1,6-dimethylcyclohexene, 3-ethylcyclohexene,
1,2,3,3-tetramethylcyclopentene, 1-ethylcyclohexene,
1,2-dimethylcyclohexene, 1-methylcycloheptene,
1,5,5-trimethylcyclohexene, 1,4,4-trimethylcyclohexene,
1,5,6-trimethylcyclohexene, cyclooctatetraene,
1,3,5-trimethylcyclohexene, cyclooctene,
1,4,5-trimethylcyclohexene, 1-vinylcyclohexene,
1,6,6-trimethylcyclohexene, 1-ethyl-4-methylcyclohexene,
1,2,3-trimethylcyclohexene, 1-ethyl-5-methylcyclohexene,
allylcyclohexene, 1,4,4-trimethylcycloheptene, cis-cyclodecene, and
combinations thereof. These olefins are either commercially
available or may be synthesized by methods known in the art.
[0239] Exemplary olefins having the formula cyclic
C.sub.nR.sub.2n-4, wherein each R is independently H or a C1-C4
hydrocarbyl group and n=5 or 7-11, provided that n.noteq.6, include
cyclopentadiene, 1,3-cycloheptadiene, 1,4-cycloheptadiene,
1,4-cyclooctadiene, 1,5-cyclooctadiene, 4-methyl-3,5-octadiene,
7-methyl-2,4-octadiene, or combinations thereof. These olefins are
either commercially available or may be synthesized by methods
known in the art.
[0240] Exemplary olefins having the formula cyclic
C.sub.nR.sub.2n-6, wherein each R is independently H or a C1-C3
hydrocarbyl group and n=7-11, include 1,3,5-cycloheptatriene,
1,3,5-cyclooctatriene, and combinations thereof. These olefins are
either commercially available or may be synthesized by methods
known in the art.
[0241] Preferably the olefin has a boiling point between
approximately room temperature and 70.degree. C. Exemplary olefins
having this boiling point include 1,4-pentadiene, 1-pentene,
2-methyl-1-butene, 3-methylcyclobutene, 2-methyl-1,3-butadiene,
trans-2-pentene, cis-2-pentene, 1-methylcyclobutene,
2-methyl-2-butene, 3-methyl-1-2-butadiene, cyclopentadiene,
1,3-pentadiene (piperylene),3,3-dimethyl-1-butene,
1-trans-3-pentadiene, 1-cis-3-pentadiene, cyclopentene,
1,2-pentadiene, 2,3-pentadiene, 4-methyl-1-pentene,
3-methyl-1-pentene, 3-methyl-1,4-pentadiene, 2,3-dimethyl-1-butene,
2,3-dimethyl-2-butene, 2-methyl-1,4-pentadiene,
4-methyl-cis-2-pentene, 4-methyl-trans-2-pentene, 1,5-hexadiene,
2-methyl-1-pentene, 1-hexene, 2-ethyl-1-butene,
trans-1,3-hexadiene, 3-methylcyclopentene, cis-3-hexene,
trans-3-hexene, 2-methyl-2-pentene, trans-2-hexene, cis-2-hexene,
1,4-hexadiene, and combinations thereof.
[0242] Even more preferably, the anhydrous olefin is selected from
cis/trans 2-pentene, 1-pentene, 1-hexene, 1,5-hexadiene,
2-methyl-1,3-butadiene, 2,3-dimethyl-2-butene,
3,3-dimethyl-1-butene, 4-methyl-1-pentene, cyclopentene, or
combinations thereof.
[0243] The molar ratio of the tungsten (VI) halide to the anhydrous
olefin is between 0.5:1 and 2:1 and preferably between 1:1 and
1.8:1. However, as demonstrated in the following examples, a large
excess of olefin leads to low tungsten (V) halides yields and
formation of unwanted by-products. Therefore, the molar ratio of
Tungsten (VI) halide to the anhydrous olefin is preferably 0.6:1 to
1.8:1. As further demonstrated in the following examples, a slight
excess of olefin leads to the complete conversion to the lower
valence tungsten halides (V or lower) which are more suitable for
separation by sublimation. Therefore, the molar ratio of tungsten
(VI) halide to anhydrous olefin is more preferably 0.6:1 to
1.8:1.
[0244] The mixture is stirred for approximately 10 min to
approximately 48 hours at a temperature range of approximately
10.degree. C. to approximately the boiling point of the olefin or
solvent, preferably from approximately 10.degree. C. to
approximately 50.degree. C., and more preferably at approximately
room temperature. The reaction mixture is stirred using a stirrer
and at a speed sufficient to maintain any solid reactant or product
in suspension. For larger batches, a double bladed stirrer may be
required to maintain the solid reactants in suspension. For
example, in a 22 L reactor, the stirrer may spin at a range of
approximately 50 rpm to approximately 500 rpm, preferably from
approximately 150 rpm to approximately 300 rpm. One of ordinary
skill in the art will recognize that the reactor size and shape
will dictate the speed needed to maintain the solid reactants in
suspension. The mixture produced comprises tungsten (IV) halide,
tungsten (V) halide, unreacted Tungsten (VI) halide, all suspended
in the mixture, the solvent in liquid form, haloalkanes, and
possible impurities.
[0245] After reaction, the reaction product may be isolated from
the mixture by evaporating the volatiles, such as the solvent or
any other volatile components of the mixture. The mixture may be
stirred in vacuo. The mixture may also be warmed to temperatures
ranging from approximately 30.degree. C. to below the boiling point
of the solvent. In another alternative, the mixture may be stirred
in vacuo and warmed. The resulting solid product is a mixture of
the WCl.sub.5 with any unreacted WCl.sub.6 and overreacted
WCl.sub.4.
[0246] Alternatively, the reaction mixture may be filtered to
remove the solvent, the by-products and impurities. Typical filters
include glass or polymer frit filters. The WX5-containing
composition may then be purified by successive washings with a
rinse solvent and dried by vacuo. Once again, the rinse solvent
must be dry (anhydrous) in order to prevent the formation of
oxygenated species, such as tungsten oxides or oxyhalides. The
rinse solvent may contain between approximately zero ppm and
approximately 100 ppm moisture. Preferably, the rinse solvent
contains between approximately zero ppm and approximately 10 ppm
moisture.
[0247] In another alternative, the reaction mixture may be filtered
to remove the solvent, by-products, and impurities and rinsed, as
above, followed by vacuum evaporation of any remaining volatiles
components
[0248] The rinse solvent may be the same or different from the
reaction solvents disclosed above. Exemplary rinse solvents include
dichloromethane, chloroform, 1-chloropropane, 2-chloropropane,
1-chlorobutane, 2-chloro-butane, pentane, heptane, octane,
ethylbenzene, xylenes. Preferably, the rinse solvent is halogen
containing solvents and low boiling points solvents because the
removal by high vacuum will be facilitated. Other rinse solvents
having properties similar to dichloromethane are also preferable in
the disclosed methods.
[0249] The isolated WX.sub.5-containing composition comprises
between approximately 60% w/w to approximately 100% w/w
WX.sub.5.
Silane Reaction
[0250] Alternatively, disilane or polysilane may be used in place
of the olefin. The reactions are described in the following
equations:
2 WX.sub.6 (s)+Si.sub.2R.sub.6 (l).fwdarw.2 WX.sub.5 (s)+2
SiR.sub.3X (l)
(2n-2) WX.sub.6 (s)+Si.sub.nR.sub.2n+2 (g, l or s).fwdarw.(2n-2)
WX.sub.5 (s)+2 SiR.sub.3X (l)+(n-2) SiR.sub.2X.sub.2 (l)
wherein g=gas; l=liquid; s=solid; X=Cl or Br; each R is
independently H, a C1-C4 hydrocarbyl group, preferably H or Me, or
a halide; and n=3-8. No more than 3 Rs should be a halide. One of
ordinary skill in the art will recognize that the required molar
concentration of the polysilane will be less than the required
molar concentration of the disilane. More particularly, the molar
ratio of the polysilane having the formula Si.sub.nR.sub.2n+2 to
the tungsten (VI) hexahalide will be between approximately
2/(5n-5):1 and approximately 3/(5n-5):1. For example,
Si.sub.3Me.sub.8 requires half the molar concentration of
Si.sub.2Me.sub.6; Si.sub.4Me.sub.10 requires 1/3 the molar
concentration of Si.sub.2Me.sub.6; etc.
[0251] Tungsten hexahalide (i.e., WX.sub.6) is added to a reactor.
WCl.sub.6 and WBr.sub.6 are commercially available. The disilane is
added to form a heterogeneous mixture at a temperature ranging from
approximately 10.degree. C. to approximately 50.degree. C. The
mixture is stirred to form a stirred heterogeneous mixture at a
speed sufficient to maintain any solids in suspension. For example,
in a 22 L reactor, the stirrer may spin at a speed ranging from
approximately 50 rpm to approximately 500 rpm, preferably from
approximately 150 rpm to approximately 300 rpm. The solid tungsten
halide product is isolated from the stirred mixture
[0252] As in the olefin reaction, care must be taken to ensure that
the tungsten halide reactant has a purity ranging from
approximately 90% mol/mol to approximately 100% mol/mol.
Preferably, the tungsten halide has a purity ranging from
approximately 95% mol/mol to approximately 100% mol/mol, and more
preferably from approximately 98% mol/mol to approximately 100%
mol/mol. Similarly, the tungsten oxyhalides, other tungsten
halides, and tungsten oxides contents in the tungsten (VI) halide
reactant may range from approximately 0% mol/mol to approximately
10% mol/mol, preferably from approximately 0% mol/mol to
approximately 5% mol/mol, and more preferably from approximately 0%
mol/mol to approximately 1% mol/mol.
[0253] The tungsten (VI) halide may be added to a reactor
containing the disilane or polysilane or vice versa. In other
words, the order of addition is not important with regard to the
final product. However, adding the tungsten (VI) halide to the
disilane or polysilane may lower the yield of the
WX.sub.5-containing composition and produce over-reduced
by-products. The disilane or polysilane may be added to a reactor
containing the tungsten (VI) halide to form a suspension at a
temperature ranging from approximately 10.degree. C. to
approximately 50.degree. C., preferably ranging from approximately
15.degree. C. to approximately 28.degree. C. As the reaction is
exothermic, external cooling may be used to maintain the
temperature below 50.degree. C. The tungsten (VI) halide reactant
will remain at least partially solid, producing a suspension in the
disilane or polysilane during the reaction. The pressure in the
reactor is preferably around atmospheric pressure (approximately 91
kPa to approximately 112 kPa).
[0254] The ratio of the tungsten (VI) halide to the disilane ranges
from approximately 0.4 molar equivalents to approximately 0.6 molar
equivalents of disilane per approximately 1 molar equivalent of
tungsten (VI) halide, preferably from approximately 0.45 molar
equivalents to approximately 0.55 molar equivalents of disilane per
approximately 1 molar equivalent of tungsten (VI) halide. One of
ordinary skill in the art will recognize that the appropriate
stoichiometric molar ratio for reactions using polysilanes will be
the disilane molar concentration divided by the number of Si--Si
bonds in the corresponding polysilane. For example, the ratio of
trisilane to tungsten (VI) halide is chosen from the range of
approximately 0.2 molar equivalents to approximately 0.3 molar
equivalents of trisilane per approximately 1 molar equivalent of
tungsten (VI) halide, preferably from approximately 0.22 molar
equivalents to approximately 0.28 molar equivalents of trisilane
per approximately 1 molar equivalent of tungsten (VI) halide; and
the ratio of tetrasilane to tungsten (VI) halide is chosen from the
range of approximately 0.13 molar equivalents to approximately 0.2
molar equivalents of tetrasilane per approximately 1 molar
equivalent of tungsten (VI) halide, preferably from approximately
0.15 molar equivalents to approximately 0.18 molar equivalents of
tetrasilane per approximately 1 molar equivalent of tungsten (VI)
halide.
[0255] A disilane or polysilane having the formula Si.sub.2R.sub.6,
Si.sub.nR.sub.2n+2, or Si.sub.nR.sub.2n, wherein each R is
independently H or a C1-C4 hydrocarbyl group, or a halide, and
n=3-8, is added to the reactor containing the tungsten (VI) halide
to produce a mixture at a temperature ranging from approximately
10.degree. C. to approximately 50.degree. C., preferably ranging
from approximately 10.degree. C. to approximately 28.degree. C.,
and more preferably at approximately room temperature (i.e.,
approximately 20.degree. C. to approximately 27.degree. C.). The
disilane or polysilane may be added as a gas, liquid, or solid.
When the disilane or polysilane is a gas, the gas may be captured
or dissolved in a solvent prior to introduction into the reactor.
Alternatively, the gas disilane or polysilane may be bubbled into a
tungsten (VI) halide/solvent mixture. When the disilane or
polysilane is a solid, a solvent capable of dissolving or
suspending the disilane or polysilane may also be used. The
disilane or polysilane and any solvents should be anhydrous and
preferably contain between approximately zero ppmv and
approximately 100 ppmv moisture to prevent the formation of
oxygenated species, such as tungsten oxides or oxyhalides. The
pressure in the reactor preferably remains around atmospheric
pressure for safety and cost reasons. However, one of ordinary
skill in the art will recognize that the reaction may also be
performed in a pressure reactor without deviating from the
teachings herein.
[0256] Exemplary disilanes having the formula Si.sub.2R.sub.6,
wherein each R is independently H, a C1-C4 hydrocarbyl group, or a
halide, include Si.sub.2Me.sub.6, Si.sub.2HMe.sub.5,
Si.sub.2H.sub.2Me.sub.4, Si.sub.2H.sub.3Me.sub.3,
Si.sub.2H.sub.4Me.sub.2, Si.sub.2Me.sub.5Cl, Si.sub.2Me.sub.5Br,
Si.sub.2HMe.sub.4Cl (Me.sub.2HSi--SiMe.sub.2Cl),
Si.sub.2HMe.sub.4Br (Me.sub.2HSi--SiMe.sub.2Br),
Si.sub.2Me.sub.4CH.sub.2Cl, Si.sub.2H.sub.6,
Si.sub.2Cl.sub.2Me.sub.4, Si.sub.2Br.sub.2Me.sub.4,
Si.sub.2Cl.sub.3Me.sub.3, Si.sub.2Br.sub.3Me, Si.sub.2Et.sub.6,
Si.sub.2MeEt.sub.5, Si.sub.2Me.sub.5Et.sub.5,
Si.sub.2H.sub.2Me.sub.2Et.sub.2 (Me.sub.2HSi--SiHEt.sub.2),
Si.sub.2H.sub.2Me.sub.3.sup.iPr (Me.sub.2HSi--SiHMe.sup.iPr),
Si.sub.2HMe.sub.4.sup.iPr (Me.sub.2HSi--SiMe.sub.2.sup.iPr),
Si.sub.2Me.sub.5.sup.iPr, Si.sub.2H.sub.2Me.sub.2.sup.iPr.sub.2,
Si.sub.2Me.sub.3.sup.iPr.sub.3, Si.sub.2Me.sub.4.sup.iPr.sub.2,
Si.sub.2HMe.sub.2.sup.iPr.sub.3 (Me.sub.3Si--SiH.sup.iPr.sub.3),
Si.sub.2HMe.sub.2.sup.iPr.sub.3 (Me.sub.2HSi--Si.sup.iPr.sub.3),
Si.sub.2H.sub.2.sup.iPr.sub.4
(.sup.iPr.sub.2HSi--SiH.sup.iPr.sub.2), Si.sub.2HMeEt.sup.iPr.sub.3
(MeEtHSi--Si.sup.iPr.sub.3), Si.sub.2H.sub.2Me.sub.2Pr.sub.2,
MeHSi(CH.sub.2).sub.nSiHMe (n=1-4), and combinations thereof.
[0257] Exemplary polysilanes having the formula Si.sub.nR.sub.2n+2
or Si.sub.nR.sub.2n, wherein each R is independently H, a C1-C4
hydrocarbyl group, or a halide, and n=3-8, include trisilane
Si.sub.3R.sub.8, tetrasilane Si.sub.4R.sub.10, pentasilane
Si.sub.5R.sub.12, and cyclosilanes with the formula
Si.sub.nR.sub.2n, such as Si.sub.3Me.sub.8
(Me.sub.3Si-Me.sub.2Si--SiMe.sub.3), Si.sub.3H.sub.2Me.sub.6
(Me.sub.2HSi-Me.sub.2Si--SiHMe.sub.2;
Me.sub.3Si-Me.sub.2Si--SiH.sub.2Me), Si.sub.3H.sub.3Me.sub.5
(Me.sub.3Si-Me.sub.2Si--SiH.sub.3), Si.sub.3H.sub.3Me.sub.4Cl
(ClMe.sub.2Si-Me.sub.2Si--SiH.sub.3), Si.sub.4Me.sub.10
(Me.sub.3Si-Me.sub.2Si--SiMe.sub.2-SiMe.sub.3),
Si.sub.4H.sub.6Me.sub.10
(H.sub.3Si-Me.sub.2Si--SiMe.sub.2-SiH.sub.3), Si.sub.5Me.sub.12,
Si.sub.5H.sub.2Me.sub.4, Si.sub.3H.sub.2Me.sub.4
(1,1,2,2-tetramethyl-cyclotrisilane), Si.sub.6Me.sub.12
(dodecamethyl-cyclohexasilane), and combinations thereof.
[0258] A solvent may also be used in the disilane reaction. For
example, the tungsten hexahalide and a solvent may be added to a
reactor to form a suspension and the disilane or polysilane added
to the suspension. Alternatively, the disilane or polysilane may be
dissolved or suspended in the same or a different solvent. In
another alternative, a solvent may be used with both the tungsten
hexahalide and the disilane or polysilane. The solvent may be the
same as or different from the halosilane by-product. Suitable
solvents include: [0259] i) halo-silanes: R.sub.3SiX,
R.sub.2SiX.sub.2, RSiX.sub.3, SiX.sub.4, wherein each R
independently=C1-C4 alkyl or hydrogen and X=Cl and Br. Exemplary
halo-silane solvents include, but are not limited to,
Me.sub.2SiHCl, Me.sub.3SiCl, Me.sub.2EtSiCl, Et.sub.2MeSiCl,
Et.sub.3SiCl, Me.sub.2PrSiCl, Me.sub.2SiHBr, Me.sub.3SiBr,
Me.sub.2EtSiBr, Et.sub.2MeSiBr, Et.sub.3SiBr, Me.sub.2PrSiBr,
Me.sub.2SiCl.sub.2, MeEtSiCl.sub.2, Et.sub.2SiCl.sub.2,
Me.sub.2SiBr.sub.2, MeEtSiBr.sub.2, Et.sub.2SiBr.sub.2,
MeSiCl.sub.3, EtSiCl.sub.3, iPrSiCl.sub.3, MeSiBr.sub.3,
EtSiBr.sub.3, PrSiBr.sub.3, SiCl.sub.4, SiBr.sub.4, and
combinations thereof; [0260] ii) halo-alkanes: R--X, with R>C3
and X=F; Cl, Br, I. Exemplary halo-alkane solvents include, but are
not limited to, C.sub.4H.sub.9--X, C.sub.5H.sub.11--X,
C.sub.7H.sub.13--X, and combinations thereof; [0261] iii)
halo-cycloalkane: R--X, with R>C5 and X=F; Cl, Br, I. Exemplary
halo-cycloalkane solvents include, but are not limited to,
C.sub.5H.sub.9--X, C.sub.6H.sub.11--X, C.sub.7H.sub.13--X, and
combinations thereof; [0262] iv) R--X.sub.2, with R>C1 and X=F;
C, Br, I. Exemplary R--X.sub.2 solvents include, but are not
limited to, CH.sub.2Cl.sub.2, CH.sub.2ClBr, CH.sub.2Cl--I,
C.sub.2H.sub.4Cl.sub.2, C.sub.2H.sub.4ClF, and combinations
thereof; [0263] v) R--X.sub.n, with R>C1, X=F, C, Br, I, and n=3
or 4. Exemplary R--X.sub.n solvents include, but are not limited
to, CHCl.sub.3, CHClF.sub.2, CHCl.sub.2F, CClF.sub.3, and
combinations thereof; [0264] vi) halo-arene: (Ar--X, with Ar=phenyl
or substituted phenyl ring with a formula as R.sub.5Ph-X, each R
may be independently H, C1-C4 alkyl, or halide (F, Cl, Br, I), and
X=F, C, Br, I. Exemplary halo-arene solvents include, but are not
limited to, Me-C.sub.6H.sub.5--X, C.sub.6H.sub.4X.sub.2, and
combinations thereof; [0265] vii) or any combinations thereof.
Preferably, the X halide in the solvent is the same as the X halide
in the reactants and products, but one of ordinary skill in the art
will recognize that any C--X bond is very strong and will not break
and contaminate the reactants or products. As a result, the X
halide in any C--X containing solvents may differ from the X halide
in the reactants and products.
[0266] A halide X from WX.sub.6 cleaves the Si--Si bond of the
disilane or polysilane to produce a halosilane by-product. The
halosilane by-product from the disilane or linear polysilane
reactants is R.sub.3SiX, wherein each R is independently H, a C1-C4
hydrocarbyl group, or a halide, and X is from the WX.sub.6
reactant. Exemplary R.sub.3SiX halosilane by-products include, but
are not limited to, Me.sub.3SiCl, Me.sub.3SiBr, Et.sub.3SiCl,
Et.sub.3SiBr, iPr.sub.3SiCl, iPr.sub.3SiBr, Me.sub.2SiHCl, or
Me.sub.2SiHBr. The halosilane by-product from linear or cyclic
polysilanes is R.sub.2SiX.sub.2, wherein each R is independently H,
a C1-C4 hydrocarbyl group, or a halide. Exemplary R.sub.2SiX.sub.2
halosilane by-products include, but are not limited to
Me.sub.2SiCl.sub.2, Me.sub.2SiBr.sub.2, Et.sub.2SiCl.sub.2,
Et.sub.2SiBr.sub.2, iPr.sub.2SiCl.sub.2, iPr.sub.2SiBr.sub.2,
MeSiHCl.sub.2, or MeSiHBr.sub.2. The halosilane by-products from
polysilane reactants may include both R.sub.3SiX and
R.sub.2SiX.sub.2.
[0267] The halosilane by-product may also be used as a solvent for
the synthesis process. The Me.sub.3SiX halosilane by-products have
a low boiling point, making subsequent removal easy (i.e.,
57.degree. C. for Me.sub.3SiCl and 79.degree. C. for
Me.sub.3SiBr).
[0268] Applicants have surprisingly discovered that the halosilane
by-product may help lower the amount of impurities in the final
WCl.sub.5 product. The halosilane by-product is water reactive and
acts as a self-drying solvent, which keeps the reaction media
moisture free. In addition, the halosilane by-product reacts and
removes any tungsten oxyhalides. Applicants further believe that
the Me.sub.3SiX halosilane by-product may scavenge some of the
elemental impurities. As shown in the Examples that follow, the
disilane reaction produces higher purity WX.sub.5 products than the
olefin reaction.
[0269] The mixture is stirred for approximately 10 min to
approximately 48 hours at a temperature range of approximately
10.degree. C. to approximately the boiling point of the halosilane
by-product, preferably from approximately 10.degree. C. to
approximately 50.degree. C., and more preferably at approximately
room temperature. The reaction mixture is stirred using a stirrer
and at a speed sufficient to maintain any solid reactant or product
in suspension. For larger batches, a double bladed stirrer may be
required to maintain the solid reactants in suspension. The mixture
produced comprises tungsten (IV) halide, tungsten (V) halide,
unreacted Tungsten (VI) halide, all suspended in the halosilane
by-product in liquid form, and possible impurities.
[0270] The concentration of the disilane or polysilane in the
halosilane by-product may be monitored to monitor progress of the
reaction. The reaction is complete when all of the disilane or
polysilane reactant is consumed.
[0271] When the disilane or polysilane and halosilane by-product
are both liquids, such as Si.sub.2Me.sub.6 and Me.sub.3SiX, the
process does not require the use of a solvent. More particularly,
WX.sub.5 may be synthesized without the use of any hydrocarbons or
chloroalkanes, further minimizing potential sources of contaminants
or additional hazardous materials, like volatile organic compounds
or carcinogens.
[0272] After reaction, the reaction product may be isolated from
the mixture by evaporating the halosilane by-product. The mixture
may be stirred in vacuo. The mixture may also be warmed to
temperatures ranging from approximately 30.degree. C. to below the
melting point of the tungsten chlorides. In another alternative,
the mixture may be stirred in vacuo and warmed. The resulting solid
product is a mixture of the WCl.sub.5 with any unreacted WCl.sub.6
and overreacted WCl.sub.4.
[0273] Alternatively, the reaction mixture may be filtered to
remove the halosilane by-products and impurities. Typical filters
include glass or polymer frit filters. Larger scale filtering
processes use polymer filter bags, such as those sold by Rosedale
Products, Inc. or Pall Corp. Tungsten (V) halide may then be
purified by successive washings with a rinse solvent and dried by
vacuo. The halosilane by-product may be used as the rinse solvent.
Once again, the rinse solvent must be dry (anhydrous) in order to
prevent the formation of oxygenated species, such as tungsten
oxides or oxyhalides. The rinse solvent may contain between
approximately zero ppm and approximately 100 ppm moisture.
Preferably, the rinse solvent contains between approximately zero
ppm and approximately 10 ppm moisture.
[0274] In another alternative, the reaction mixture may be filtered
to remove the halosilane by-product and impurities and rinsed, as
above, followed by vacuum evaporation of any remaining volatiles
components.
[0275] Applicants have surprisingly discovered that the silane
reaction produces a high quantity of WX.sub.5 in the isolated
WX.sub.5-containing composition. More particularly, the isolated
WX.sub.5-containing composition comprises between approximately 85%
w/w to approximately 100% w/w WX.sub.5, preferably between
approximately 90% w/w and approximately 100% w/w WX.sub.5, and more
preferably between approximately 95% w/w and approximately 100%
WX.sub.5. This is surprising because Traven et al. disclose a
similar process that quickly converts WCl.sub.6 to WCl.sub.4.
Izvestiya Akademii Nauk SSR, Seriya Khimicheskaya (1975) 7, p. 1681
(32% conversion after 5 minutes). One of ordinary skill in the art
having Traven et al. before them would not expect the change in
stoichiometry and solvent to produce high yields of the 1.sup.st
reduction product, WX.sub.5.
[0276] The Tungsten (V) halide reaction product from either
synthesis process may be further purified by sublimation under
reduced pressure at temperatures below the melting point of the
desired product. For example, WCl.sub.5 may be purified by
sublimation under vacuum at temperatures below approximately
248.degree. C., and more preferably below approximately 220.degree.
C. Unreacted Tungsten (VI) halide, over-reduced tungsten (IV)
halide, and other impurities may be removed by sublimation.
[0277] The purified Tungsten (V) halide has a purity ranging from
approximately 96% mol/mol to approximately 100% mol/mol, preferably
from approximately 98% mol/mol to approximately 100% mol/mol. The
purified Tungsten (V) halide preferably has between the detection
limit and 100 ppb of each potential metal contaminant (e.g., at
least Al, Ca, Cr, Cu, Fe, Mg, Ni, K, Na, Ti, Zn, etc.). Suitable
sublimation methods include fractional sublimation. The fractional
sublimation may be performed at high temperatures and
sub-atmospheric pressure.
[0278] As shown in the following Examples, Applicants have
surprisingly discovered that the impurity profile from the disilane
synthesis is very low. More particularly, prior to sublimation, the
WCl.sub.5 reaction product contains less than 150 ppbw of Al, Ca,
and TI; less than 1000 ppbw of Li, Mn, and Zn; less than 10,000
ppbw Cr, Mo, and Na; and less than 20,000 ppbw Fe. Sublimation
further reduces the impurities to less than 150 ppbw for Al, Ca,
Cr, Fe, Li, Mn, Na, Tl, and Zn and less than 200 ppbw Mo.
[0279] In contrast, even after sublimation, the amount of Cr, Fe,
Mo, Na, and Zn remaining in the WCl.sub.5 produced by the olefin
method remains between approximately 100 ppbw to approximately 6000
ppbw.
[0280] One of ordinary skill in the art will recognize the sources
for the components of the systems used to practice the disclosed
methods. Preferably the components are made of corrosion resistant
materials, including but not limited to glass, glass or polymer
coated stainless steel, fluoropolymers such as perfluoroalkoxy
alkane (PFA) and polytetrafluoroethylene (PTFE), etc.
[0281] The product may be analyzed by Ultraviolet-Visible (UV-VIS)
spectroscopy, Fourier Transform InfraRed (FTIR) spectroscopy,
ThermoGravimetric Analysis-Differential Thermal Analysis (TGA-DTA),
Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD),
X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron
Microscopy (SEM), elemental analysis, and other analytical
technique
[0282] In the examples that follow, the purity of the
WX.sub.5-containing composition was determined using TGA-DTA. One
of ordinary skill in the art will recognize that TGA is just one of
many analysis techniques that may be utilized to determine
purity.
[0283] Applicants have further determined that aluminum pans are
not suitable for TGA analysis of the WX.sub.5-containing
composition. Instead, alumina pans were used for all TGA analysis
(i.e., alumina=aluminum oxide).
[0284] TGA is a thermal analysis technique which measures the
amount and rate of change in the weight of a material as a function
of temperature or time in a controlled atmosphere. DTA measures the
temperature differences between a sample and inert reference
undergoing identical thermal cycles. DSC is similar to DTA and
measures the difference in the amount of heat required to increase
the temperature of a sample and a reference as a function of
temperature. These thermal analytical techniques may identify
characteristic melting and sublimation points, phase transitions
and decompositions. TGA measurements are also used to predict
thermal stability up to elevated temperatures and to determine the
composition of materials by studying the loss of solvents and/or
volatile compounds for example; species or impurities contained in
the sample are released during the weight loss event in the TGA.
TGA curves may also show the presence of impurities.
[0285] FIG. 2 is a TGA plot illustrating the percentage of weight
loss upon temperature increase of WCl.sub.4, WCl.sub.5, and a
controlled mixture of the two. As shown in FIG. 2, the presence of
WCl.sub.4 in WCl.sub.5 caused a step feature ranging from
approximately 250.degree. C. to approximately 390.degree. C. and an
increase in the total amount of residue. The differences in the TGA
curves may be quantified by weight loss measurements, comparison
with mass loss of pure standards (e.g. WCl.sub.4, WCl.sub.6), or
using TGA derivatives. Derivative TGA curves are useful to
distinguish overlapped mass loss events, to identify a trend and
maximum rate of mass loss processes, and also to identify a small
mass loss steps. Thus, application of first (DTG), second (2DTG),
and third (3DTG) derivatives of the TGA curves allows monitoring
and identification of small amounts of impurities in tungsten
halides producing strongly overlapped features on the TGA curves.
Using this simple and rapid technique, data from TGA/DTA can be
used to identify qualitatively and to determine quantitatively the
amount of common impurities in tungsten chlorides including but not
limited to WCl.sub.4, WCl.sub.5, and WCl.sub.6.
[0286] The weight loss measurement in the region specific to the
impurity may be quantified. The size and position of any feature
(dip or step) on the TGA trace due to the presence of the impurity
maybe measured and correlated to the amount of the impurity (%) in
the sample. The weight loss for analyzed samples may be compared
with that of a standard (e.g. pure WCl.sub.4, WCl.sub.5), and the
concentration of WCl.sub.4, WCl.sub.6, and other impurities
established by application of any available mathematical
method.
[0287] FIG. 1 is a diagram of an exemplary system suitable to
perform the disclosed methods. One of ordinary skill in the art
will recognize that additional components may be included without
departing from the teachings herein. More particularly, the reactor
10 may include any monitors needed to monitor the reaction, such as
pressure, temperature, etc. Air may be removed from various parts
of the system (e.g., reactor 10) by an inert gas 2, such as
nitrogen, argon, etc. The inert gas 2 may also serve to pressurize
the solvent stored in vessel 5, rinse solvent stored in vessel 3,
and/or olefin or disilane stored in vessel 4 to permit its delivery
to reactor 10. One of ordinary skill in the art will recognize that
only vessel 3 or 5 will be needed when the solvent and rinse
solvent are the same.
[0288] The reactor 10 is maintained at the desired temperature by a
jacket 11. The jacket 11 has an inlet 21 and an outlet 22. Inlet 21
and outlet 22 may be connected to a heat exchanger/chiller 23
and/or pump (not shown) to provide recirculation of the cooling
fluid. Nitrogen, refrigerated ethanol, an acetone/dry ice mixture,
silicone oils, or other heat transfer agents such as monoethylene
glycol (MEG) may be used to cool various parts of the system (e.g.,
jacket 11). The cooling medium (not shown) in jacket 11 may also be
replaced by a heating medium (not shown) when needed, for example,
to evaporate the solvent and isolate the reaction product. One of
ordinary skill in the art will recognize that "replacement" of the
cooling medium will not be necessary if the cooling medium is also
capable of acting as a heating medium (e.g., MEG). Instead, the
temperature of the medium may be changed via, for example, heat
exchanger. The temperature is monitored with a probe 29.
[0289] One of ordinary skill in the art will recognize that the
jacket 11 may not require inlet 21 and outlet 22 If the batch size
is small enough and the mixing time short enough because the
thermal fluid may maintain its temperature for the duration of the
reaction. Alternatively, the jacket 11 may not be required if the
batch size is small enough and the mixing time long enough because
heat may be vented to the atmospheric environment during the
reaction. In another alternative, the temperature of the reactor 10
may be maintained using a cold finger, cooling foil, or other
temperature control mechanisms in addition to or replacing the
jacket 11.
[0290] The reactants (solvent stored in vessel 5, Tungsten (VI)
halide stored in vessel 1, and olefin/disilane stored in vessel 4)
are added to reactor 10 via lines 6, 7, and 8, respectively. One of
ordinary skill in the art will recognize that solid reactants may
alternatively be added to the reactor 10 using addition funnels or
other solid movement tools. One of ordinary skill in the art will
further recognize that lines 6, 7, and/or 8 may further comprise
additional equipment that adds the reactants and/or solvents to the
vessel 10 in a controllable manner, such as gauges, glass addition
funnels, calibrated follow meters, piston metering pumps, etc.
[0291] The reactants may be mixed in the reactor by an agitator 12
turned by motor 13 to form mixture 14. The mixing is performed
under an inert atmosphere at approximately atmospheric pressure.
After suitable mixing, the mixture 14 may be stirred in vacuo to
remove the volatiles which are trapped in cold trap 27 connected to
a vacuum pump 28. Once the volatiles are evaporated, the solid
products may be removed from the reactor 10 under inert atmosphere
prior to performance of the next process steps.
[0292] Instead of evaporation in vacuo, the mixture 14 may be
removed from reactor 10 via drain 15 through a container 18
connected to a filter 17. In this embodiment, reactor 10 will most
likely be located above filter 17 to best use the benefits of
gravity. The inert gas 2 may be used to help move the mixture 14
into the drain 15. Alternatively, the mixture 14 may be removed
from the reactor 10 using any slurry movement tools, such as a
slurry pump (not shown), to move the mixture 14 into the filter 17.
As the tungsten halide (not shown) is suspended in the mixture 14,
clogging of the reactor 10 is not a problem. The rinse solvent
stored in vessel 3 can be added to the reactor 10 via line 9 after
the filtration process in order to remove residual products,
by-products, and/or impurities.
[0293] The solid product will be collected in container 16, such as
a glass bottle, and transported to a new location prior to
performance of the next process steps. Alternatively, the mixture
may immediately be directed to a pot 19, without passing though the
filter 17.
[0294] Once again, vessel 18 may be transported to a new location
prior to performance of the next process steps. The product may be
transferred from vessel 18 to a sublimator (not shown) for further
purification.
[0295] One of ordinary skill in the art will recognize that the
exemplary system may include many additional elements that are not
described in order to provide a simplified view of the system. For
example, one of ordinary skill in the art will recognize that the
gases may be introduced into the reactor through a pressure valve
and mass flow controller. Additionally, one of ordinary skill in
the art will recognize that additional valves, pumps, and flow
controllers may be located at various other locations without
departing from the teachings herein.
EXAMPLES
[0296] The following non-limiting examples are provided to further
illustrate embodiments of the invention. However, the examples are
not intended to be all inclusive and are not intended to limit the
scope of the inventions described herein.
Example 1. Synthesis of Tungsten Pentachloride from
Hexamethyldisilane
[0297] 4900 g WCl.sub.6 and 12 kg of trimethylsilyl chloride
(TMS-Cl) were charged into a 22 L reactor and the mixture was
stirred at 150 rpm. With external cooling, hexamethyldisilane
(HMDS) 870 g was added slowly over a period of 3.5 hrs, during
which the reaction mixture temperature increased from room
temperature to about 50.degree. C. The mixture was stirred for
another 1.5 hrs to allow cooling below 35.degree. C. The mixture
was then filtered and the collected solid was washed with 3 Kg of
TMS-Cl, followed by solvent removal and drying under vacuum. The
solid WCl.sub.5 product was purified using sublimation.
[0298] The purity of the reaction product was assessed by
thermogravimetric analysis (TGA). A typical pure tungsten (V)
pentachloride displays a smooth evaporation with a step feature of
1-2% and a residue of <1%. An increase of the step feature
indicates an overreduction to tungsten (IV) tetrachloride. The
absence of the step shows the presence of unreacted tungsten (VI)
hexachloride. A right shift of the overall evaporation curve can
also be associated with the presence of tungsten (VI) hexachloride
at high levels.
[0299] FIG. 3 is the ThermoGravimetric Analysis/Differential
Thermal Analysis (TGA/DTA) plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the WCl.sub.5 product before sublimation.
The amount of residue of the step (4%) shows the presence of
overreduced tungsten (IV) tetrachloride. The step shows that there
is little to no tungsten (VI) hexachloride. As a result,
approximately 96% WCl.sub.5 was formed by this reaction.
[0300] FIG. 4 is a TGA/DTA plot illustrating the percentage of
weight loss (TGA) or the differential temperature (DTA) upon
temperature increase of the WCl.sub.5 product after sublimation.
The amount of residue of the step (1.2%) shows that the overreduced
tungsten (IV) tetrachloride has been significantly reduced by
sublimation. As a result, approximately 99% WCl.sub.5 was obtained
after sublimation.
[0301] Sublimation of the reaction product may be used to further
purify the WCl.sub.5 product.
Example 2. Impurity Profile from Disilane Reaction
[0302] WCl.sub.5 samples were obtained from Example 1 before and
after sublimation. The hydrolyzed WCl.sub.5 samples were directly
injected for ionization in a nebulizer in an Inductively Coupled
Plasma Mass Spectrometer (ICP-MS). The results were as follows:
TABLE-US-00001 Metals (in ppbw) Pre-sublimation Post sublimation Al
100 ND Sb ND ND As ND ND Ba ND ND Be ND ND Cd ND ND Ca 64 ND Cr
2500 ND Co ND ND Cu ND ND Ga ND ND Ge ND ND In ND ND Fe 18000 ND Pb
ND ND Li 240 ND Mg 87 ND Mn 720 ND Mo 2200 190 Ni ND ND Nb ND ND K
ND ND Ag ND ND Na 1300 ND Sr ND ND Tl 56 ND Sn ND ND Ti ND ND V ND
ND Zn 220 ND Zr ND ND ND = None detected, Detector limit is below
50 ppbw.
Example 3
[0303] Additional WCl.sub.5 products were obtained from the
disilane reactions after sublimation. The hydrolyzed WCl.sub.5
samples were directly injected for ionization in a nebulizer in an
ICP-MS. The results were as follows:
TABLE-US-00002 Metals (in Batch Batch Batch Batch Batch Batch Batch
Batch Batch ppbw) 1 2 3 4 5 6 7 8 9 Al ND ND ND ND ND 130 63 ND ND
Sb ND ND ND ND ND ND ND ND ND As ND ND ND ND ND ND ND ND ND Ba ND
ND ND ND ND ND ND ND ND Be ND ND ND ND ND ND ND ND ND Cd ND ND ND
ND ND ND ND ND ND Ca ND ND ND ND ND ND ND ND ND Cr ND 51 ND ND ND
ND ND ND ND Co ND ND ND ND ND ND ND ND ND Cu ND ND ND ND ND ND ND
ND ND Ga ND ND ND ND ND ND ND ND ND Ge ND ND ND ND ND ND ND ND ND
In ND ND ND ND ND ND ND ND ND Fe ND 120 ND ND ND ND ND ND 71 Pb ND
ND ND ND ND ND ND ND ND Li ND ND ND ND ND 78 ND ND ND Mg ND ND ND
ND ND ND ND ND ND Mn ND ND ND ND ND ND ND ND ND Mo 190 ND 120 130
ND 75 130 140 96 Ni ND ND ND ND ND ND ND ND ND Nb ND ND ND ND ND ND
ND ND ND K ND ND ND ND ND ND ND ND ND Ag ND ND ND ND ND ND ND ND ND
Na ND ND ND ND ND ND ND ND ND Sr ND ND ND ND ND ND ND ND ND Tl ND
ND ND 78 ND ND 51 ND ND Sn ND ND ND ND ND ND ND ND ND Ti ND ND ND
ND ND ND ND ND ND V ND ND ND ND ND ND ND ND ND Zn ND ND ND ND ND ND
ND ND ND Zr ND ND ND ND ND ND ND ND ND ND = None detected, Detector
limit is below 50 ppbw.
Example 4. Synthesis of Tungsten Pentachloride in 1-Chlorobutane
with Stoichiometric Amounts of Cis/Trans-2-Pentene
[0304] Under an inert atmosphere, a reaction flask is charged with
tungsten (VI) hexachlode (2.48 g; 0.007 mol). 1-chlorobutane (20
mL; 17.5 g; 0.189 mol) and cis/trans-2-pentene (0.46 g; 0.007 mol)
are added to the reaction flask. The reaction mixture is stirred
under inert atmosphere for 3 hours. The reaction may stop upon
exhaustion of the cis/trans-2-pentene reactant but was stopped in
this example by removing all volatiles under vacuum.
[0305] FIG. 5 is a TGA/DTA plot of the product of Example 4. The
amount of residue of the step (4%) shows the presence of
overreduced tungsten (IV) tetrachloride. These results demonstrate
a smaller step as compared to those in the following comparative
examples, showing the improved purity of crude tungsten (V)
pentachloride using a stoichiometric amount of reactants and an
aliphatic halohydrocarbon solvent. Sublimation of the reaction
product may be used to further purify the WCl.sub.5 product.
Example 5. Synthesis of Tungsten Pentachloride in Dichloromethane
with Close to Stoichiometric Amounts of Cis/Trans Pentene
[0306] Under inert atmosphere, a reaction flask is charged with
tungsten (VI) hexachloride (9.9 g; 0.025 mol). Anhydrous
CH.sub.2Cl.sub.2 (80 mL; 105 g; 1.5 mol) and cis/trans-2-pentene
(1.84 g; 0.026 mol) are added to the reaction flask. The reaction
mixture is stirred under inert atmosphere for 30 minutes. The
reaction is stopped by removal of all volatiles under vacuum.
[0307] FIG. 6 is a TGA/DTA plot of the product of Example 5. The
amount of residue of the step (6%) shows the presence of
over-reduced tungsten (IV) tetrachloride.
Example 6. Olefin Synthesis Impurity Profile
[0308] WCl.sub.5 samples were obtained from Example 5 after
sublimation. The hydrolyzed WCl.sub.5 samples were directly
injected for ionization in a nebulizer in an ICP-MS. The results
were as follows:
TABLE-US-00003 Metals Batch Batch Batch Batch Batch Batch Batch (in
ppbw) 1 2 3 4 5 6 7 Al 1000 ND 210 ND ND 150 100 Sb ND ND ND ND ND
ND ND As ND ND ND 270 110 ND ND Ba ND ND ND ND ND ND ND Be ND ND ND
ND ND ND ND Cd ND ND ND ND ND ND ND Ca 160 ND 1800 ND ND 380 220 Cr
210 ND ND ND ND ND ND Co ND ND ND ND ND ND ND Cu ND ND ND ND ND ND
ND Ga ND ND ND ND ND ND ND Ge ND ND ND ND ND ND ND In ND ND ND ND
ND ND ND Fe 5100 2000 1500 ND ND 380 150 Pb ND ND ND ND ND ND 230
Li ND ND ND ND ND ND ND Mg 260 ND ND ND ND ND ND Mn ND ND ND ND ND
ND ND Mo ND ND ND ND ND ND ND Ni 200 ND ND ND ND ND ND Nb 180 210
ND ND ND ND ND K 310 ND ND 1100 970 78 97 Ag ND ND ND ND ND ND ND
Na 730 ND ND ND ND ND ND Sr ND ND ND 130 120 ND ND Tl ND 78 ND ND
ND 91 74 Sn ND ND ND ND ND ND ND Ti ND ND ND ND ND ND ND V 61 ND ND
ND ND ND ND Zn ND ND ND ND ND 3500 ND Zr ND ND ND ND ND ND ND ND =
None detected, Detector limit is below 50 ppbw.
As can be seen from the comparison of Examples 2, 3, and 6, the
WCl.sub.5 disilane synthesis produces significantly less impurities
than the WCl.sub.5 olefin synthesis.
Comparative Example 1. Synthesis of Tungsten Pentachloride in
Pentane with Excess of Cis/Trans Pentene
[0309] Under inert atmosphere, a reaction flask is charged with
tungsten (VI) hexachloride (4.96 g; 0.013 mol). Anhydrous pentane
(40 mL; 25 g; 0.35 mol) and cis/trans-2-pentene (2.10 g; 0.030 mol)
are added to the reaction flask. The reaction mixture is stirred
under inert atmosphere for 15 hours. The reaction is stopped by
removal of all volatiles under vacuum.
[0310] FIG. 7 is a TGA/DTA plot of the product of Comparative
Example 1. The absence of the step shows the presence of unreacted
tungsten (VI) hexachloride along with a non-smooth evaporation seen
by the right shift at the bottom half of the curve. This
comparative example demonstrates that the aliphatic halohydrocarbon
of Examples 1 and 2 yields a larger quantity of the desired product
than reactions using hydrocarbons.
Comparative Example 2. Synthesis of Tungsten Pentachloride in
Dichloromethane with Excess of Cis/Trans Pentene
[0311] Under inert atmosphere, a reaction flask is charged with
tungsten (VI) hexachloride (9.9 g; 0.025 mol). Anhydrous
CH.sub.2Cl.sub.2 (80 mL; 105 g; 1.5 mol) and cis/trans-2-pentene
(17.5 g; 0.25 mol) are added to the reaction flask. The reaction
mixture is stirred under inert atmosphere for 30 minutes. The
reaction is stopped by removal of all volatiles under vacuum.
[0312] FIG. 8 is a TGA/DTA plot of the product of Comparative
Example 2. The increased presence of the step (36%) shows the
presence of over-reduced tungsten (IV) tetrachloride along with an
increased residue. This comparative example demonstrates that a
stoichiometric excess of olefin rapidly drives the reaction past
the desired WCl.sub.5 product to the lower oxidation state
WCl.sub.4.
[0313] While embodiments of this invention have been shown and
described, modifications thereof may be made by one skilled in the
art without departing from the spirit or teaching of this
invention. The embodiments described herein are exemplary only and
not limiting. Many variations and modifications of the composition
and method are possible and within the scope of the invention.
Accordingly the scope of protection is not limited to the
embodiments described herein, but is only limited by the claims
which follow, the scope of which shall include all equivalents of
the subject matter of the claims.
* * * * *