Bridged cyclopentadienylmagnesium compounds and use thereof for preparing metallocenes

Claim 1

A compound of the general formula (1) Q(CpR.sub.a)(Cp'R'.sub.a ')Mg (1) wherein Cp is a cyclopentadienyl or an indenyl radical; R and R' are the same or different and each is selected from the group consisting of alkyl, phosphine, amino, alkylamino, dialkylamino, alkoxy, alkoxy-alkyl, aryl-alkyl, and aryloxy-alkyl groups; 0≦a≦4 and 0≦a'≦4; Cp' is cyclopentadienyl or indenyl, or when a' is 1, Cp'R' can be NR" wherein R" is a C 1 -C 12 alkyl or a C 6 -C 10 aryl radical; and Q is a single-membered or multi-membered bridge between Cp and Cp' and represents (R.sup.1 --Z--R.sup.2).sub.b, wherein R 1 and R 2 are identical or different and each is a hydrogen atom, a C 1 -C 10 alkyl group or a C 6 -C 10 -aryl group; Z is carbon, silicon or germanium; and b is 1, 2 or 3.