Patent ID: RE39156

Claim:
A compound of the formula I in its pure meso-form or as a meso:rac>1:99 mixture, in which M 1 is a metal from group IVb, Vb or VIb of the Periodic Table, R 1 and R 2 are identical or different and are a hydrogen atom, a C 1 -C 10 -alkyl group, a C 1 -C 10 -alkoxy group, a C 6 -C 10 -aryl group, a C 6 -C 10 -aryloxy group, a C 2 -C 10 -alkenyl group, a C 7 -C 40 -arylalkyl group, a C 7 -C 40 -alkylaryl group, a C 8 -C 40 -arylalkenyl group, or a halogen atom, the radicals R 4 and R 5 are identical or different and are a hydrogen atom, a halogen atom, a C 1 -C 10 -alkyl group, which may be halogenated, a C 6 -C 10 -aryl group, which may be halogenated, or an —NR 10 2 , —SR 10 , —OSiR 10 3 , —SiR 10 3 or —PR 10 2 radical in which R 10 is a halogen atom, a C 1 -C 10 -alkyl group or a C 6 -C 10 -aryl group, R 3 and R 6 are identical or different and are as defined as for R 4 , with the proviso that R 3 and R 6 are not hydrogen, or two or more of the radicals R 3 to R 6 , together with the atoms connecting them, form a ring system, >BR 11 , >AlR 11 , —Ge—, —Sn—, —O—, —S—, >SO, >SO 2 , >NR 11 , >CO, >PR 11 or >P(O)R 11 , where R 11 , R 12 and R 13 are identical or and R 12 are different and are a hydrogen atom, a halogen atom, a C 1 -C 10 -alkyl group, a C 1 -C 10 -fluoroalkyl group, a C 6 -C 10 -aryl group, a C 6 -C 10 -fluoroaryl group, a C 1 -C 10 -alkoxy group, a C 2 -C 10 -alkenyl group, a C 7 -C 40 -arylalkyl group, a C 8 -C 40 -arylalkenyl group or a C 7 -C 40 -alkylaryl group, R 13 is a hydrogen atom, a halogen atom, a C 1 -C 10 - alkyl group, a C 1 -C 10 - fluoroalkyl group, a C 6 -C 10 - aryl group, a C 6 -C 10 - fluoroaryl group, a C 1 -C 10 - alkoxy group, a C 2 -C 10 - alkenyl group, a C 7 -C 40 - arylalkyl group, a C 8 -C 40 - arylalkenyl group or a C 7 -C 40 - alkylaryl group, or R 11 and R 12 or R 11 and R 13 , in each case together with the atoms connecting them, form a ring, M 2 is silicon, germanium or tin, R 8 and R 9 are identical or different and are as defined for R 11 , and m and n are identical or different and are zero, 1 or 2, where m plus n is zero, 1 or 2.