Metallocenes with 2-substituted indenyl-derivates as ligands, process for their preparation and their use as catalysts

摘要

The metallocenes of the formula I according to the invention

in which the substituents have the following preferred meanings: M<1> is Zr or Hf, R<1> and R<2> are alkyl or halogen, R<3> and R<4> are hydrogen, R<5> and R<6> are alkyl or haloalkyl, -(CR<8>R<9>)m-R<7>-(CR<8>R<9>)n- is a chain with one or more than one members in which R<7> can also be a (substituted) hetero atom, m + n is zero or 1 and R<10> is hydrogen, form, together with aluminoxanes as cocatalysts, a highly effective catalyst system for the preparation of polyolefins which have a high stereospecificity and high melting point.