STEREOCHEMISTRY OF FIRST MONOMER INSERTION INTO METAL-METHYL BOND - ATOOL FOR EVALUATING LIGAND-MONOMER INTERACTIONS IN PROPENE POLYMERIZATION WITH METALLOCENE CATALYSTS

Propene has been polymerized with three different metallocene complexe s: Me2Si(Ind)(2)ZrCl2 (I), Me2Si(BenzInd)(2)ZrCl2 (II), and Me2Si(MeBe nzInd)(2)ZrCl2 (III) by using C-13-enriched cocatalyst MAO/Al((CH3)-C- 13)(3). The stereochemical analysis of selectively C-13-enriched methy l chain end groups has shown that, while a moderate first step enantio selectivity is present with catalyst I, the bulky benzannelated substi tuents (catalysts II and III) lead to an almost total lack of steric c ontrol on the first monomer insertion. The methyl substitution in the a-position of cyclopentadienyl ring (catalyst III) does not seem to in fluence the choice of the face.