Metallocene catalysts comprising indenyl ligands substituted with electronegative groups

摘要

A highly effective catalyst system for the polymerization of olefins comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I where M1=Zr or Hf, R1 and R2=(C1-C3)-alkyl or chlorine, R3, with the proviso that at least one of the radicals R3 is not hydrogen, is hydrogen, F, Cl, -OR7, -NR7R8, -P(O)R7R8, -P(OR7)2 or SR7, R4 is a radical, and m plus n are zero or 1.