Preparation of doubly-silylene-bridged zirconocene alkyl complexes, (Me2Si)2{η5-C5H 2-4-CHMe2}{η5-C5H-3,5-(CHMe 2)2}ZrR2(R = CH3, CH2Ph) and investigations of their activity in 1-pentene polymerization.

Article abstract of DOI:10.1016/s0020-1693(98)00061-9

The syntheses of the doubly-[SiMe₂]-bridged zirconocene complexes, (Me₂Si)₂{η⁵-C₅H ₂-4-CHMe₂}{η⁵-C₅H-3,5-(CHMe ₂)₂}ZrR₂ (R = Cl (2); R = CH₂Ph (3); R = CH₃ (4)) are described. The structure of (Me₂Si)₂{η⁵-C₅H ₂-4-CHMe₂}{η⁵-C₅H-3,5-(CHMe ₂)₂}-Zr(CH₂Ph)₂ (3) has been examined by single crystal X-ray diffraction methods. It crystallizes in the triclinic space group P-1, with a = 9.900(2), b = 11.818(2), c = 15.320(3) A?, α = 105.02(3), β = 92.56(3), γ = 105.23(3)° and Z=2. Compounds 3 and 4 are active stereospecific pre-catalysts for the [Ph₃C] [B(C₆F₅)₄] co-catalyzed polymerization of 1-pentene. Polymerization reactions at low temperature in liquid monomer produced poly(1-pentene) with syndiotactic microstructure and narrow molecular weight distribution. By contrast, in 1-pentene/toluene solutions a broad molecular weight distribution is observed. Under all conditions examined 2/MAO systems produced high molecular weight, highly syndiotactic poly-1-pentene with narrow molecular weight distributions.