Si 2Me 4-bridged zirconocene dichlorides: crystal and molecular structure of meso-Si 2Me 4(3-SiMe 3–C 9H 5) 2ZrCl 2

Abstract

A series of complexes Si 2Me 4L 2ZrCl 2 (L=Ind ( 1b), 2-Me–Ind ( 2b), 3-SiMe 3–Ind ( 3b) and Ind–H 4 ( 4)) was prepared. The syntheses of 1b, 3b and 4 gave predominantly the meso-isomers, whereas a 1:1 meso: rac mixture was obtained for 2b. X-ray analysis of meso- 3b revealed large steric hindrance on the metal center (Cp°–Zr–Cp° is 134.6°). The 1:1 mixture of meso- 2b and rac- 2b (activated with MAO) produced a 2.2:1 mixture of elastic atactic and isotactic polypropylene with low activity.