C1-bridged fluorenylidene cyclopentadienylidene complexes of the type (C13H8-CR1R2-C5H3R)ZrCl2 (R1, R2 = alkyl, phenyl, alkenyl;: R = H, alkyl, alkenyl, substituted silyl) as catalyst precursors for the polymerization of ethylene and propylene

The synthesis and characterization of 14 new C-1-bridged fluorenylidene cyclopentadienylidene complexes of zirconium is described. After activation with methylaluminoxane (MAO), these metallocene complexes can be used for the polymerization of ethylene and propylene. Various substituents in the bridge and in position 3 of the cyclopentadienylidene ligand have a strong influence on the activity of the corresponding catalysts and the molecular weights of the formed polyolefins. The bulkiness of the substituents in position 3 of the cyclopentadienylidene ring determines the extent of the stereospecific polymerization of propylene. Substituents can be selected that produce hemitactic, syndiotactic or isotactic polypropylenes and/or the corresponding block copolymers. (C) 1998 Elsevier Science S.A. All rights reserved.