Conversion of cyclopentadienyl silyl amines to organometallic complexes comprising titanium bisalkoxy moiety or titanium dichloride moiety

This invention relates to titanium organometallic complexes which comprise a titanium bisalkoxy moiety or a titanium dichloride moiety.

U.S. Pat. Nos. 5,491,246 and 5,504,223 describe the treatment of Me 4 C 5 SiMe 2 N t -bu[MgCl] 2 (DME) n with titanium tetraisopropoxide to provide Me 4 C 5 SiMe 2 N t BuTi(OiPr) 2 which may be treated with SiCl 4 to yield the corresponding dichloride.

In this specification, the following expressions have the meanings set forth hereinafter:

(1) Cyclopentadienyl means any substituted or unsubstituted cyclopentadienyl compound, group or moiety, including but not limited to any alkylcyclopentadienyl, any indenyl, or any alkyl indenyl compound, group or moiety having one or more C 1 to C 10 alkyl ring substituents.

(2) Alkoxide means any radical or group having the formula —OR, wherein R is an alkyl group.

(3) Cyclopentadienyl silyl amine means a compound of Formula

in which Z is a cyclopentadienyl group or moiety and each of R 1 , R 2 and R 3 is independently, the same or a different alkyl group, preferably a C 1 to C 10 alkyl group.

Pursuant to this invention, an alkali metallide of a cyclopentadienyl silyl amine is reacted with a titanium tetraalkoxide Ti(OR) 4 in which R is a C 1 to C 10 alkyl group, preferably an isopropyl group. The reaction mixture contains the desired bisalkoxide and, as a by-product, an alkali metal alkoxide which may be isolated or converted in situ to an insoluble alkali metal halide to facilitate removal by filtration. The filtrate contains the desired bisalkoxide which may be converted to the corresponding dichloride by treatment with a halogenating agent, e.g., SiCl 4 .

The treatment of a silyl amine with Ti(OR) 4 may be accomplished in any solvent or medium in which the desired titanium bisalkoxide is soluble. Preferred solvents or media are about 10% to 25% by weight mixtures of ethyl ether and a C 6 to C 8 hydrocarbon. The treatment may be accomplished at a temperature of from about −20° to −10° C. The conversion of the alkali metal alkoxide by-product to an alkali metal halide insoluble in the solvent contained in the titanium bisalkoxide synthesis reaction mixture is appropriately conducted at a temperature of from about −35° to −20° C. Conversion of the bisalkoxide to the corresponding dichloride may be accomplished in situ in the synthesis reaction mixture at a temperature of −20° C. to room temperature or refluxing temperature. Useful halogenating agents include SiCl 4 , BCl 3 , and AlCl 3 .

2-Me-indenyl SiMe 2 NH t Bu is dilithiated by treatment with butyllithium, e.g., in a 50 weight percent hexane/ether medium at −20° C. See Equation 1:

The dilithiated silyl amine is treated with titanium tetraisopropoxide at a temperature of −35° C., wherein a reaction mixture comprising indenyl SiMe 2 NH t Bu titanium isopropoxide and lithium isopropoxide is produced. See Equation 2:

The reaction mixture is treated with SiCl 4 in an amount, e.g., 0.6 equiv, sufficient to convert LiOiPR in situ to LiCl which is removed by filtration. A hexane wash of the cake may be combined with the mother liquor which is a solution of the desired titanium bisisopropoxide complex in hexanes/ether.

1.5 equivalents of SiCl 4 are added to the LiCl-free mother liquor which contains the titanium bis(isopropoxide) complex to provide a second reaction mixture which is refluxed for six hours, and cooled to precipitate the desired titanium dichloride complex for removal by filtration. The cake is washed with hexanes. Titanium dichloride complex yield=70% to 80% (based on the silyl amine).