Metallocene compound

A metallocene compound of the formula (I) ##STR4## where M.sup.1 is a metal of group IVb, Vb or VIb of the Periodic Table,

• R.sup.1 and R.sup.2 are identical or different and are each a hydrogen atom, a C.sub.1 -C.sub.10 -alkyl group, a C.sub.1 -C.sub.10 -alkoxy group, a C.sub.6 -C.sub.10 -aryl group, a C.sub.6 -C.sub.10 -aryloxy group, a C.sub.2 -C.sub.10 -alkenyl group, a C.sub.7 -C.sub.40 -arylalkyl group, a C.sub.8 -C.sub.40 -arylalkenyl group, an OH group or a halogen atom,
• the radicals R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are identical or different and are each a hydrogen atom, a halogen atom, a C.sub.1 -C.sub.20 -hydrocarbon radical which may be halogenated, an --NR.sub.2, --SR, --OR, --OSiR.sub.3, --SiR.sub.3 or PR.sub.2 radical, where R is a halogen atom, a C.sub.1 -C.sub.10 -alkyl group or a C.sub.6 -C.sub.10 -aryl group, or two or more of the radicals R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 together with the atoms connecting them form a ring system, and
• the radicals R.sup.3', R.sup.4', R.sup.5', R.sup.6', R.sup.7', R.sup.8', R.sup.9', R.sup.10' and R.sup.11' are identical or different and are each a hydrogen atom, a halogen atom, a C.sub.1 -C.sub.20 -hydrocarbon radical which may be halogenated, an --NR.sub.2, --SR, --OR, --OSiR.sub.3, --SiR.sub.3 or PR.sub.2 radical, where R is a halogen atom, a C.sub.1 -C.sub.10 -alkyl group or a C.sub.6 -C.sub.10 -aryl group, or two or more of the radicals R.sup.3', R.sup.4', R.sup.5', R.sup.6', R.sup.7', R.sup.8', R.sup.9', R.sup.10' and R.sup.11' together with the atoms connecting them form a ring system.