SOLUBLE CATALYST COMPOSITION FOR 2-10 C ALKENE-1 POLYMER

The present invention relates to soluble catalyst systems for the polymerization of C2- to C10-alk-l-enes, containing, as active constituents, a) a metallocene complex of the general formula I (I) where R1 and R2 are branched C4- to C10-alkyl, 5- to 7-membered cycloalkyl, which may itself be substituted by C1- to C6-alkyl, or are C6- to C15-aryl or aralkyl; R3 to R6 are C1- to C8-alkyl, M is titanium, zirconium, hafnium or vanadium, Y is silicon or germanium, and X is halogen or C1- to C8-alkyl, b) and an open-chain or cyclic aluminoxane compound of the general formula II or III where R7 is C1-C4-alkyl, and m is from 5 to 30. These catalyst systems are particularly suitable for the preparation of polypropylene and copolymers of propylene with lesser amounts of other C2- to C10-alky-l-enes.