PREPARATION OF DOUBLY-SILYLENE-BRIDGED ZIRCONOCENE ALKYL COMPLEXES, TA(5)-C5H2-4-CHME2)(ETA(5)-C5H-3,5-(CHME2)(2))ZRR2 (R = CH3, CH2PH) ANDINVESTIGATIONS OF THEIR ACTIVITY IN 1-PENTENE POLYMERIZATION - MOLECULAR-STRUCTURE OF H2-4-CHME2)(ETA(5)-C5H-3,5-(CHME2)(2))ZR(CH2PH)(2)

The syntheses of the doubly-[SiMe2]-bridged zirconocene complexes, ta( 5)-C5H2-4-CHMe2}{eta(5)-C5H-3,5-(CHMe2)(2)}ZrR2 (R = Cl (2), R = CH2Ph (3); R = CH3 (4)) are described. The structure of -4-CHMe2}{eta(5)C(5 )H-3,5-(CHMe2)(2)}-Zr(CH2Ph)(2) (3) has been examined by single crysta l X-ray diffraction methods. It crystallizes in the triclinic space gr oup P-l, with a=9.900(2), b=11.818(2), c=15.320(3) Angstrom, alpha=105 .02(3), beta=92.56(3), gamma=105.23(3)degrees and Z=2. Compounds 3 and 4 are active stereospecific pre-catalysts for the [Ph3C] [B(C6F5)(4)] co-catalyzedpolymrrization of I-pentene. Polymerization reactions at low temperature in liquid monomer produced poly(l-pentene) with syndio tactic microstructure and narrow molecular weight distribution. By con trast, in 1-pentene/toluene solutions a broad molecular weight distrib ution is observed. Under all conditions examined 2/MAO systems produce d high molecular weight, highly syndiotactic poly-1-pentene with narro w molecular weight distributions. (C) 1998 Elsevier Science S.A. All r ights reserved.