Asymmetric silicon-bridged metallocenes useful as catalysts in the polymerization of a-olefins, process for their preparation and use of said metallocenes for the polymerization of a-olefins

摘要

Asymmetric silicon-bridged metallocenes useful as catalysts in the polymerization of olefins and process for preparing said metallocenes. The metallocenes are represented by the general formula: wherein M represents a transition metal selected from Ti, Zr and Hf, X and X' represent a halogen atom, R<1>, R<2>, R<3> represent an alkyl group containing 1 or 2 carbon atoms or a hydrogen atom, providing that at least two of R<1>, R<2>, R<3> are alkyl groups, and R<4> and R<5> represent an alkyl or aryl group containing from 1 to 10 carbon atoms. Process for producing the metallocenes of general formula (I) comprising the steps of: a) reacting dichloro-dialkyl(or diaryl)silane with (substituted indenyl)lithium to produce (substituted indenyl)-dialkyl(or diaryl)-chlorosilane, b) reacting said chlorosilane with fluorenyllithium to produce the (9-fluorenyl)-1-(substituted indenyl)-dialkyl(or diaryl)-silane precursor, c) reacting said (9-fluorenyl)-1-(substituted indenyl)-dialkyl(or diaryl)-silane precursor with butyllithium to produce its dilithium salt, and d) reacting said dilithium salt with a transition metal halide selected from halides of Ti, Zr and Hf to produce the metallocenes. Process for the polymerization of alpha -olefins such as ethylene and propylene by means of said metallocene.