Alkene-platinum-silyl complexes

Details Alkene-platinum-silyl complexes Alkene-platinum-silyl complexes

2001-12-07

2003-08-12

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S012000, C556S479000, C556S465000, C502S152000, C502S158000

Reexamination Certificate

active

06605734

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to alkene-platinum-silyl complexes described by formula (I) (COD)Pt(SiR
1
3−n
)
2
Y
n
, where each R
1
is independently selected from organic groups, halo atoms, and siloxy groups, each Y is an independently selected divalent bridging group between the silicon atoms bonded to platinum, n is 0, 1, 2, or 3, and COD is 1,5-cyclooctadiene.
BACKGROUND OF THE INVENTION
Platinum compounds and complexes are well known catalysts for organic reactions, such as hydrosilation (or hydrosilylation), generally in amounts 5 to 100 parts per million mol per mol non-aromatic, multiple bond. Many so-called homogeneous platinum hydrosilation catalysts including the well-known Speier's Catalyst and Karstedt's Catalyst, though widely used, suffer from one or more disadvantages, such as loss of active platinum via precipitation at higher temperatures, slow catalysis rates for bulky or deactivated alkenes and concurrent side reactions, such as isomerization of the olefin. It is therefore desirable to find platinum hydrosilation catalysts that overcome one or more of the above disadvantages suffered by many known general purpose catalysts, and are also readily prepared, relatively inexpensive, and can provide high rates of reaction. A further positive attribute in such catalysts would be the ability to reuse the initial charge of catalyst without loss of activity, since platinum is a rare and precious metal with very low natural abundance.
The inventors have now discovered novel alkene-platinum-silyl complexes which are highly active catalysts and meet the above desirable qualities of robustness, homogeneity, ready synthesizability and maintenance of activity for repeated use.
SUMMARY OF THE INVENTION
The present invention is a class of alkene-platinum-silyl complexes described by formula (I)
(COD)Pt(SiR
1
3−n
)
2
Y
n
,
where each R
1
is independently selected from organic groups, halo atoms, and siloxy groups, each Y is an independently selected divalent bridging group between the silicon atoms bonded to platinum, n is 0, 1, 2, or 3, and COD is 1,5-cyclooctadiene. A method of making these complexes is also described.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a class of alkene-platinum-silyl complexes described by formula (I)
(COD)Pt(SiR
1
3−n
)
2
Y
n
,
where each R
1
is independently selected from organic groups, halo atoms, and siloxy groups, each Y is an independently selected divalent bridging group between the silicon atoms bonded to platinum, n is 0, 1, 2, or 3, and COD is 1,5-cyclooctadiene.
In formula (I), each R
1
is independently selected from organic groups, halogen atoms, and siloxy groups. The term “organic groups” as used herein means groups having carbon chains or rings and the substituents bonded to those carbon chains or rings may include hydrogen atoms, halo atoms and oxygen, where the oxygen may also be connecting two carbon chains or bonded directly to a silicon atom. Preferred organic groups include alkyl groups comprising 1 to 25 carbon atoms, aryl groups comprising 6 to 25 carbon atoms, and oxygen-containing organic groups.
The alkyl groups comprising 1 to 25 carbon atoms of R
1
may be linear, branched or cyclic. The alkyl groups may also be unsubstituted or substituted with halo atoms or oxygen groups. Examples of unsubstituted alkyl groups of R
1
include methyl, ethyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, dodecyl, octadecyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, 2-cyclohexylethyl, and norbornyl. Examples of substituted alkyl groups of R
1
include chloromethyl, 3-chloropropyl, 3,3,3-trichloropropyl, 3,3,3-trifluoropropyl, fluorocyclohexyl, and methoxycyclohexyl. Preferred alkyl groups are methyl, ethyl, and 3,3,3-trifluoropropyl, with methyl and 3,3,3-trifluoropropyl being most preferred.
The aryl groups comprising 6 to 25 carbon atoms of R
1
may be unsubstituted or substituted with halo atoms or oxygen groups. Examples of unsubstituted aryl groups of R
1
include phenyl, tolyl, xylyl, biphenyl, benzyl, and naphthyl. Examples of substituted aryl groups of R
1
include chlorophenyl, methoxyphenyl, and pentafluorophenyl. Preferred aryl groups are phenyl, tolyl, and chlorophenyl.
The oxygen-containing organic groups of R
1
are groups having an oxygen radical bonded either directly to a silicon atom, connecting two carbon chains or as a substituent of a carbon chain. Preferred oxygen-containing organic groups include alkoxy groups and acyloxy groups.
The alkoxy groups have a formula described by —OR
2
, where R
2
is an alkyl group comprising 1 to 25 carbon atoms. The alkyl group of R
2
may be substituted or unsubstituted. Examples of R
2
are as described above for the alkyl groups of R
1
. Specific examples of alkoxy groups useful in the invention include methoxy, ethoxy, 2-chloroethoxy, tertiarybutoxy, 2,2,2-trifluoroethoxy, pentoxy, cyclohexoxy, methoxyethoxy, bromocyclohexoxy, and methylcyclohexoxy. Preferably, R
2
is an alkyl group comprising 1 to 6 carbon atoms.
The acyloxy groups have a formula described by —O(C═O)—R
3
, where R
3
is independently selected from alkyl groups comprising 1 to 25 carbon atoms and aryl groups comprising 6 to 25 carbon atoms. The alkyl groups and aryl groups of R
3
can be substituted or unsubstituted. Examples of the alkyl groups comprising 1 to 25 carbon atoms and aryl groups comprising 6 to 25 carbon atoms of R
3
are as described above for R
1
. Specific examples of acyloxy groups useful in the invention include acetoxy, propionyloxy, benzoyloxy, chloroacetoxy, dichloroacetoxy, trichloroacetoxy, and trifluoroacetoxy. Preferably, R
3
is an alkyl group comprising 1 to 6 carbon atoms, most preferably R
3
is a methyl group.
In formula (I), each R
1
may also comprise halo atoms. Examples of these halo atoms include chloro, bromo, fluoro, and iodo atoms. Preferred halo atoms are chloro, bromo and fluoro, with chloro and bromo being most preferred.
Each R
1
may also comprise siloxy groups. It is preferred that the siloxy groups have the formula —(OSiR
4
2
)
n
—X, where each R
4
and X are independently selected from alkyl groups comprising 1 to 25 carbon atoms, aryl groups comprising 6 to 25 carbon atoms, halo atoms, and oxygen-containing organic groups and n is 1 to 6. Examples of the alkyl groups and aryl groups of R
4
and X are as described above for R
1
. Examples of oxygen-containing organic groups are also as described above for R
1
. Preferred siloxy groups include —OSiMe
3
, —OSiMe
2
Ph, —OSiMe
2
CH
2
CH
2
CF
3
, and —OSiMe
2
OSiMe
3
, where Me means methyl and Ph means phenyl.
It is most preferred that each R
1
is independently selected from methyl, phenyl, 3,3,3-trifluoropropyl, and chloro.
In formula (I), each Y group is an independently selected divalent bridging group between the silicon atoms bonded to platinum. This divalent bridging group may be comprised of —(OSiR
1
2
)
m
—O— units, where R
1
is as described above and m is from 0 to 3, or divalent hydrocarbon groups comprising 1 to 5 carbon atoms. For example, the bridged siloxy structure may be based on linear siloxanes, cyclic siloxanes or silsesquioxanes, and the bridging hydrocarbon structure may be an alkylene such as —CH
2
CH
2
— or an arylene such as ortho-phenylene.
Subscript n describes how many R
1
groups and Y groups are bonded to each silicon atom bonded to platinum. Subscript n is an integer from 0 to 3. Preferably n is 0 or 1.
The other important ingredient of the present invention is COD which is 1,5-cyclooctadiene. The COD is bound to platinum in an eta-4 bonding mode.
Another embodiment of the present invention relates to methods of contacting COD, platinum, and SiH-containing silanes or siloxanes in sufficient amounts to make the alkene-platinum-silyl complexes described by formula (I) (COD)Pt(SiR
1
3−n
)
2
Y
n
, where R
1
, Y, n, and COD are as described above. These methods include premixing the COD and SiH-containing silane or siloxane prior to the addition of the platinum and premixing the COD and platinum

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