| abstract |
Catalyst systems for the polymerization of C 2 -C 10 -alkenes contain, as active components, a metallocene complex of a metal of subgroup IV or V of the Periodic Table, an oligomeric alumina compound and a cyclic boron compound of the general formula IV ##STR1## where R 18 to R 20 are each C 1 -C 10 -alkyl which may be monosubstituted to trisubstituted by halogen, C 6 -C 15 -aryl or C 1 -C 10 -alkoxy, n C 4 -C 7 -cycloalkyl which may be monosubstituted to trisubstituted by halogen, C 1 -C 10 -alkyl or C 1 -C 10 -alkoxy, n C 1 -C 10 -alkoxy which may be monosubstituted to trisubstituted by halogen, C 1 -C 10 -alkyl or C 6 -C 15 -aryl, or C 6 -C 15 -aryl which may be monosubstituted to pentasubstituted by halogen, C 1 -C 10 -alkyl or C 1 -C 10 -alkoxy. |