STEREOCHEMISTRY OF FIRST MONOMER INSERTION INTO A METAL-METHYL BOND -ENANTIOSELECTIVITY AND DIASTEREOSELECTIVITY IN 3-METHYL-1-PENTENE POLYMERIZATION WITH METALLOCENE CATALYSTS

The stereochemistry of first monomer insertion in the polymerization o f racemic 3-methyl-1-pentene ((RS)-3MP1) with three different metalloc ene complexes, Me(2)Si(Ind)(2)ZrCl2 (I), Me(2)Si(BenzInd)(2)ZrCl2 (II) , and Me(2)Si(MeBenzInd)(2)ZrCl2 (III), in the presence of MAO/Al((CH3 )-C-13)(3) cocatalyst has been studied and the results have been compa red to those previously obtained using the traditional isospecific TiC l3/Al((CH3)-C-13)(3) heterogeneous catalyst. The highest enantioselect ivity and diastereoselectivity are observed with the least hindered me tallocene (catalyst I). While enantioselectivity decreases due to benz annelation of the ligand with catalyst II, the methyl substitution in the 2-position of the cyclopentadienyl rings with catalyst III causes an almost complete lack of diastereoselectivity.