Patent ID: 7671223

Claim:
A process for the racemoselective preparation of ansa-metallocene complexes of the formula (I): the process comprising reacting a ligand starting compound of the formula (II): with a transition metal compound of the formula (III): (LB) y M 1 (NR 3 R 4 )X x-1 (III) where R 1 , R 1′ are identical or different and are each hydrogen or an organic radical having from 1 to 40 carbon atoms; R 2 , R 2′ are identical or different and are each hydrogen or an organic radical having from 1 to 40 carbon atoms; R 3 is an organic radical having from 1 to 40 carbon atoms; R 4 is hydrogen or an organic radical having from 1 to 40 carbon atoms; T, T′ are identical or different and are each a divalent organic group which has from 1 to 40 carbon atoms and together with the cyclopentadienyl ring forms at least one further saturated or unsaturated, substituted or unsubstituted ring system which has a ring size of from 5 to 12 atoms, where T and T′ may contain the heteroatoms Si, Ge, N, P, As, Sb, O, S, Se or Te within the ring system fused to the cyclopentadienyl ring; A is a bridge consisting of a divalent atom or a divalent group; M 1 is an element of group 3, 4, 5 or 6 of the Periodic Table of the Elements or the lanthanides; the radicals X are identical or different and are each a halogen or an organosulfunate group; x is a natural number from 3 to 6; M 2 is an alkali metal, an alkaline earth metal or a magnesium monohalide fragment; p is 1 in the case of doubly positively charged metal ions or is 2 in the case of singly positively charged metal ions or metal ion fragments; LB is an uncharged Lewis-base ligand; and y is a natural number from 0 to 6.