Process for the preparation of polyolefins

A process for the preparation of an olefin polymer by polymerization or copolymerization of an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b, in which R.sup.a and R.sup.b are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or R.sup.a and R.sup.b, together with the atoms connecting them, can form a ring, at a temperature of from -60.degree. to 200.degree. C., at a pressure of 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of a catalyst formed from a metallocene in the meso-form or a meso:rac mixture, with meso:rac>1:99, as transition-metal compound and a cocatalyst, wherein the metallocene is a compound of the formula I, ##STR17## in which M.sup.1 is a metal from group IVb, Vb or VIb of the Periodic Table,

• R.sup.1 and R.sup.2 are identical or different and are 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.7 -C.sub.40 -alkylaryl group, a C.sub.8 -C.sub.40 -arylalkenyl group, or a halogen atom,
• the radicals R.sup.4, R'.sup.4 and R.sup.5 are identical or different and are a halogen atom, a C.sub.1 -C.sub.10 -alkyl group, which may be halogenated, a C.sub.6 -C.sub.10 -aryl group, which may be halogenated, and an --NR.sup.10.sub.2, --SR.sup.10, --OSiR.sup.10.sub.3, --SIR.sup.10.sub.3 or --PR.sup.10.sub.2 radical in which R.sup.10 is a halogen atom, a C.sub.1 -C.sub.10 -alkyl group or a C.sub.6 -C.sub.10 -aryl group, and additionally, R.sup.4 and R.sup.5 can also be hydrogen,
• R.sup.3 and R.sup.6 are identical or different and are as defined for R.sup.4, with the proviso that R.sup.3 and R.sup.6 are not hydrogen, or two or more of the radicals R.sup.3 to R.sup.6, together with the atoms connecting them, form a ring system,
• R.sup.7 is ##STR18## >BR.sup.11, >AlR.sup.11, --Ge--, --Sn--, --O--, --, >SO, >SO.sub.2, >NR.sup.11, >CO, >PR.sup.11 or >P(O)R.sup.11, where R.sup.11, R.sup.12, and R.sup.13 are identical or different and are a hydrogen atom, a halogen atom, a C.sub.1 -C.sub.10 -alkyl group, a C.sub.1 -C.sub.10 -fluoroalkyl group, a C.sub.6 -C.sub.10 -aryl group, a C.sub.6 -C.sub.10 -fluoroaryl group, a C.sub.1 -C.sub.10 -alkoxy 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 or a C.sub.7 -C.sub.40 -alkylaryl group, or R.sup.11 and R.sup.12 or R.sup.11 and R.sup.13, in each case together with atoms connecting them, form a ring,
• M.sup.2 is silicon, germanium or tin,
• R.sup.8 and R.sup.9 are identical or different and are as defined for R.sup.11, and
• m and n are identical or different and are zero, 1 or 2, where m plus n is zero, 1 or2.

A method of using a metallocene as a catalyst in the preparation of an olefin polymer by polymerizing or copolymerizing an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b, in which R.sup.a and R.sup.b are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or R.sup.a and R.sup.b, together with the atoms connecting them, can form a ring, at a temperature of from -60.degree. to 200.degree. C., at a pressure of 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of the metallocene catalyst and a cocatalyst, where the metallocene is a compound of the formula I in its pure meso-form or as a meso:rac>1:99 mixture ##STR19## in which M.sup.1 is a metal from group IVb, Vb or VIb of the Periodic Table,

• R.sup.1 and R.sup.2 are identical or different and are 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.7 -C.sub.40 -alkylaryl group, a C.sub.8 -C.sub.40 -arylalkenyl group, or a halogen atom,
• the radicals R.sup.4 and R.sup.5 are a hydrogen atom, identical or different and are a halogen atom, a C.sub.1 -C.sub.10 -alkyl group, which may be halogenated, a C.sub.6 -C.sub.10 -aryl group, which may be halogenated, and an --NR.sup.10.sub.2, --SR.sup.10, --OSiR.sup.10.sub.3, --SiR.sup.10.sub.3 or --PR.sup.10.sub.2 radical in which R.sup.10 is a halogen atom, a C.sub.1 -C.sub.10 -alkyl group or a C.sub.6 -C.sub.10 -aryl group,
• R.sup.3 and R.sup.6 are identical or different and are as defined for R.sup.4, with the proviso that R.sup.3 and R.sup.6 are not hydrogen, or two or more of the radicals R.sup.3 to R.sup.6, together with the atoms connecting them, form a ring system,
• R.sup.7 is ##STR20## >BR.sup.11, >AlR.sup.11, --Ge--, --Sn--, --O--, --S--, >SO, >SO.sub.2, >NR.sup.11, >CO, >PR.sup.11 or >P(O)R.sup.11, where R.sup.11, R.sup.12, and R.sup.13 are identical or different and are a hydrogen atom, a halogen atom, a C.sub.1 -C.sub.10 -alkyl group, a C.sub.1 -C.sub.10 -fluoroalkyl group, a C.sub.6 -C.sub.10 -aryl group, a C.sub.6 -C.sub.10 -fluoroaryl group, a C.sub.1 -C.sub.10 -alkoxy 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 or a C.sub.7 -C.sub.40 -alkylaryl group, or R.sup.11 and R.sup.12 or R.sup.11 and R.sup.13, in each case together with atoms connecting them, form a ring,
• M.sup.2 is silicon, germanium or tin,
• R.sup.8 and R.sup.9 are identical or different and are as defined for R.sup.11, and
• m and n are identical or different and are zero, 1 or 2, where m plus n is zero, 1 or 2.