NEW ANSA-METALLOCENES OF THE GROUP-4 TRANSITION-METALS AS HOMOGENEOUS CATALYSTS FOR THE POLYMERIZATION OF PROPENE AND STYRENE

The ansa-bridged metallocenes [M{CR2(eta-C5H4)(eta-C9H6)}Cl2], [M = Ti, Zr or Hf; CR2 = CMe2, CPh2 or C(CH2)5] have been prepared. The crystal structure of [Zr{CMe2(eta-C5H4)(eta-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.