Synthesis of [3]ferrocenophane-bridged Cp–amido zirconium complexes and ansa-zirconocene complexes and their use in catalytic polymerisation reactions

Abstract

Starting from 1,1′-diacetylferrocene the ortho-amino,α-dimethylamino[3]ferrocenophane system 3 was prepared. This was converted to the o-imino,α-Cp-derivative 6. Subsequent treatment with e.g. an excess of methyllithium followed by ZrCl₂(NMe₂)₂(thf)₂ and Me₂SiCl₂ eventually gave the [3]ferrocenophane based Cp–amido zirconium complex 11b. In a similar way the [3]ferrocenophane derived fluorenyl–Cp ansa-zirconocene dichloride complex 20 was obtained. The 20–methylalumoxane (MAO) system is an active homogeneous Ziegler–Natta catalyst for ethylene polymerization. The 11b–MAO system reacts efficiently with an ethene–1-octene mixture to yield a mixture of linear polyethylene plus the ethene–1-octene copolymer. The compounds 5, 8, 10b, 11b, 13, 14, and 20 were characterized by X-ray diffraction.