Thomas E. Ready

Alkyl-substituted indenyl titanium precursors for syndiospecific ziegler-natta polymerization of styrene

A variety of 1- and 3-substituted alkylindenes (R = H, Me, Et, tert-butyl, Me3Si) as well as 2-methylindene and 3-(methylthio)indene have been prepared in good yields. The substituted indenes were converted into trimethylsilyl derivatives via reactions of intermediate organolithium complexes with chlorotrimethylsilane. The corresponding titanium complexes, (R-Ind)TiCl3, were synthesized in excellent yield from reactions of the trimethylsilyl derivatives with TiCl4. The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. Activities increased in the order: Cp < H4 Ind < Ind < 1-(Me)Ind <2-(Me)Ind. A steep drop in activity was observed when R = Et, tert-butyl, and Me3Si, corresponding to an increase in the steric bulk of the substituent in the catalyst precursor. 1-(MeS)IndTiCl3 was found to be ineffective as a styrene polymerization catalyst. Syndiospecificities of the titanium complexes were generally very good (65–98%).

New indenyl titanium catalysts for syndiospecific styrene polymerizations

Abstract A series of multi-methyl-substituted indenes as well as allylindene, n -propylindene, n -but-1-enylindene, and n -butylindene have been prepared in good yields. The substituted indenes were converted into trimethylsilyl derivatives via reactions of intermediate organolithium complexes with chlorotrimethylsilane. The corresponding titanium complexes were synthesized in excellent yields from reactions of the trimethylsilyl derivatives with TiCl 4 . The titanium complexes were evaluated as styrene polymerization catalysts in toluene solution when activated by methylaluminoxane. In general, catalytic activities decreased with each additional methyl substituent. Syndiospecificities were very high (90–95%).

Binuclear monoindenyl–titanium(IV) complexes. Synthesis and styrene polymerization catalysis

Abstract The first binuclear monoindenyl–titanium(IV) complexes have been synthesized by the stepwise reaction of [1,2-C 2 H 4 (1-Ind) 2 ]Li 2 with 2 equiv of ClTi(O- i -Pr) 3 , giving a 1:1 rac and meso mixture of 1,2-C 2 H 4 [1-IndTi(O- i -Pr) 3 ] 2 ( 2 ), followed by an in situ chlorination reaction with CH 3 C(O)Cl in ethyl ether to form 1,2-C 2 H 4 [1-IndTi(O- i -Pr)Cl 2 ] 2 ( 3 ). Further reaction of 3 with CH 3 C(O)Cl in CH 2 Cl 2 afforded 1,2-C 2 H 4 [1-IndTiCl 3 ] ( 4 ). Styrene polymerization studies with methylaluminoxane (MAO) as cocatalyst demonstrated 3 and 4 to be highly syndiospecific catalyst precursors, although their activities were one order of magnitude lower than for the reference mononuclear compound IndTiCl 3 ( 1 ).