Silylene-bridged fluorenyl-containing ligands and zirconium complexes with C1 and Cs symmetry: general synthesis and olefin polymerization catalysis

Article abstract of DOI:10.1016/0022-328X(95)00118-A

A variety of new silylene-bridged fluorenyl-containing ligands has been synthesized with good yields via a convenient synthetic route.Two dimethylsilylene-bridged (η⁵-indenyl)(η⁵-fluorenyl) (1) and (η⁵-cyclopentadienyl)(η⁵-fluorenyl) (2) zirconocene dichlorides with C₁ and C_s molecular symmetry have also been prepared.Upon activation with methyl aluminoxane, the former produced a polypropylene of high molecular weight, but with low activity and isotacticity.The latter catalyzed non-stereospecific propylene polymerization without any zyndiotactic tendency, but with 40 and 20 times greater ethylene and propylene activity respectively than the former catalytic system.Keywords: Zirconium; Olefin; Polymerization catalysis; Fluorenyl ligands