| abstract |
A very effective catalyst system for olefin polymerization comprises a cocatalyst, preferably an aluminoxane, and a metallocene of the formula I in which, preferably, M1 is Zr or Hf, R1 and R2 are halogen or alkyl, R3 is alkyl, R4 to R10 are alkyl or hydrogen and R11 is a (substituted) alkylene or heteroatom bridge. |