| abstract |
A highly effective catalyst system for the polymerization of olefins comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I ##STR1## where M 1 =Zr or Hf, R 1 and R 2 =(C 1 -C 3 )-alkyl or chlorine, R 3 , with the proviso that at least one of the radicals R 3 is not hydrogen, is hydrogen, F, Cl, --OR 7 , --NR 7 R 8 , --P(O)R 7 R 8 , --P(OR 7 ) 2 or SR 7 , R 4 is a ##STR2## radical, and m plus n are zero or 1. |