New ansa-metallocenes of the Group 4 transition metals as homogeneous catalysts for the polymerization of propene and styrene

Abstract

The ansa-bridged metallocenes [M{CR₂(η-C₅H₄)(η-C₉H₆)}Cl₂], [M = Ti, Zr or Hf; CR₂= CMe₂, CPh₂ or C(CH₂)₅] have been prepared. The crystal structure of [Zr{CMe₂(η-C₅H₄)(η-C₉H₆)}Cl₂] has been determined. Some of these new ansa-metallocenes in the presence of methylaluminoxane (AlMeO)_n give homogeneous catalysts, which for the polymerization of propene yield isotactic rich polypropene and of styrene yield syndiotactic polystyrene.