DIASTEREOSELECTIVE SYNTHESIS, MOLECULAR-STRUCTURE, AND SOLUTION DYNAMICS OF HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM AND HYLENEBIS(4,7-DIMETHYL-ETA(5)-1-INDENYL])ZIRCONIUM DICHLORIDE ISOMERS AND CHAIN TRANSFER-REACTIONS IN PROPENE POLYMERIZATION WITH THE RAC ISOMER

The known hylenebis(4,7-dimethyl-eta(5)-1-indenyl)]ZrCl2(2r) and its m eso isomer (2m) have been compared with the prototypal chiral isospeci fic rac-[ethylenebis(eta(5)-1-indenyl)]ZrCl2 (1r) and its aspecific me so isomer Im in terms of molecular structures, solution dynamics, and ligand substitution effect on polymerization performance. in Liquid pr opene at 50 degrees C, 2r/MAO produces iPP with appreciably higher iso tacticity but lower molecular weight and regiospecificity than 1r/MAO. The lower molecular weight obtained with 2r in liquid monomer is due to predominant chain transfer to the monomer after a secondary propene insertion, producing >90% cis-2-butenyl- end groups. At lower propene concentration, 2r/MAO allows both beta-hydrogen transfer after a prim ary insertion and beta-methyl transfer, The low-activity 2m/MAO cataly st produces low molecular weight aPP. The diastereoselective synthesis of 2r,m via the corresponding rac- and 4,7-dimethy-1-(trimethylsilyl) -3-indenyl)ethane,is reported. The crystal and molecular structures of (4,7-dimethyl-1-(trimethylsilyl)-3-indenyl)ethane, 2r,m, have been de termined.