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(3) have been synthesized and characterized. The influence of the alkenyl substituent groups on the catalyst activities in the syndiotactic polymerization of styrene was investigated. The catalyst activities decreased in the order CH 2 CHCH 2 CH 2 CpTiCl 3 > CH 3 CH 2 CH 2 CH 2 CpTiCl 3 > CH 3 CH 2 CH 2 CpTiCl 3 > CH 2 CHCH 2 CpTiCl 3 (Cp C 5 H 4 ). By using complex 1, the dependence of the activity on the concentration of methylaluminoxane, triisobutylaluminum and diisobutylaluminum hydride was investigated.

Results and discussion Synthesis of catalyst precursorsAs shown in Scheme 1, the reaction of alkenylcyclopentadienyltrimethylsilane with Zd& -(SM& in CH,C12/ DME gave the alkenylcyclopentadienyl zirconium trichlorides (1, 2), which can be recrystallized from D W n -h e x a n e as white crystals in 6 2 % -6 9 % yields. Treatment of a CH2C12 solution of 1 or 2 with one equivalent of RC&J. i led to the formation of the desired mixed-ring zirconocene ( 3-6 ) , which can be easily recrystalhed from hot n -h e m e as white or pale yellow crystals with yields from 5 1 % to 65 % . scbemel 1) n-BuLi 2) MeSi3CI CHI= CH(CHz),,CpH CHz= CH(CH,),,CpSiMe, -n = I (I); n = 2 (2) CH~=CH(CH~),,CP n = 1, R: CH30CH2CH2 (3) \ n = 2 , R: CH30CH2CH2 (4) CI R: Me3Si (5) RCp/ Zr,, R: CH,=CHCH, (6)Complexes 1 to 6 are characterized by elemental analysis, 'H NMR, IR and mass spectra. 'H NMR spectra: the resonance for hydrogen of vinyl and rnethoxyl does not shift to higher field (low frequency). IR spectra: complexes show a band at 1620-1640 cm-' due to an uncoordinated vc-c and a band at 1100-1 120 cm-' due to an uncoordinated YC-0.