ETHYLENE POLYMERIZATIONS WITH DISILOXANE-BRIDGED INDENYL AND CYCLOPENTADIENYL METALLOCENE CATALYSTS

ansa-Tetramethyldisiloxane-bridged indenyl, tetrahydroindenyl and cycl opentadienyl zirconium complexes 1-4 were prepared. The pure rac-1-3 a nd meso-1-2 complexes were separated by fractional crystallization. In denyl complexes, both rac-1 and meso-1, in the presence of methylalumi noxane (MAO), have very high activities for ethylene polymerization. T he molecular weight of polyethylene produced with rac-1 is extremely h igh and significantly dependent on polymerization temperature. The ter t-butyl-substituted cyclopentadienyl complex exhibits low activity and produces polyethylene of low molecular weight.