Patent ID: 7342078

Claim:
A metallocene of the formula (I) where M 11 is a metal of group IVb of the Periodic Table of the Elements, R 31 , R 32 are identical or different and are each a hydrogen atom, a C 1 -C 10 -alkyl group, a C 1 -C 10 -alkoxy group, a C 6 -C 20 -aryl group, a C 6 -C 20 -aryloxy group, a C 2 -C 10 -alkenyl group, an OH group, an N(R 32a ) 2 group, where R 32a is a C 1 -C 10 -alkyl group or a C 6 -C 14 -aryl group, or a halogen atom, where R 31 and R 32 can also be joined to form a ring, R 34 , R 36 , R 37 and R 38 and also R 34′ , R 36′ , R 37′ and R 38′ are identical or different and are each a hydrogen atom or a hydrocarbon group which may be halogenated, linear, cyclic or branched, R 33 is a hydrocarbon group which is unbranched in the α position and may be halogenated, R 33 is a hydrocarbon group which is cyclized in the α position or branched in the α position and may be halogenated, R 35 , R 35′ are identical or different and are each a C 6 -C 20 -aryl group which in the para position relative to the point of linkage to the indenyl ring bears a substituent R 43 or R 43′ , or R 39 is a bridge where R 40 , R 41 can be identical or different, even when they have the same index, and are each a hydrogen atom, a halogen atom or a C 1 -C 40 group, where R 40 and R 41 may each, together with the atoms connecting them, form one or more rings, x is an integer from zero to 18, M 12 is silicon, germanium or tin, and R 39 may also link two units of the formula I with one another, R 43 is a C 1 -C 20 -alkyl radical, a C 2 -C 10 -alkenyl radical, a C 6 -C 18 -aryl radical, a C 7 -C 20 -arylalkyl radical, a C 7 -C 20 -alkylaryl radical, a C 8 -C 20 -arylalkenyl radical, where the hydrocarbon radicals may also be halogenated or partially halogenated by fluorine or chlorine, —N(R 44 ) 2 , —P(R 44 ) 2 , —SR 44 , Si(R 44 ) 3 , —[N(R 44 ) 3 ] + or —[P(R 44 ) 3 ] + , where the radicals R 44 are identical or different and are each a hydrogen atom or a hydrocarbon group which may be halogenated, linear, cyclic or branched, R 43 is hydrogen or is as defined for R 43 , R 45 , R 45′ , R 46 and R 46′ are each C 4 -C 20 -aryl, alkenyl or alkyl ring systems which may also be linked to the radicals R 36 , R 36′ or R 34 , R 34′ .