Spirane-bridged ansa η5-cyclopentadienyl-η5-fluorenyl-zirconocene precatalysts

Synthesis of rigid ansa-zirconocene precatalyst systems with a C2-bridge embedded in a spirane scaffold is described. Fulvenes were key intermediates in regio- and stereoselective preparation of the appropriate spirane ligands. Substitution in the cyclopentadienyl group in the ligand was effected by fulvene methodology. The zirconocenes were active precatalysts for the polymerisation of propene when activated with MAO. The structure of the parent zirconocene dichloride has been verified by X-ray crystal analysis.

Rigid zirconocene precatalysts with a C2-bridge embedded in spirane scaffolds have been prepared from 1- and 4-fluorenones. The intermediate ligands were lithiated and zirconated to afford η5-cyclopentadienyl-η5-fluorenyl-zirconocenes. Isopropyl homologues resulted from regioselective substitution in the cyclopentadienyl ring. The catalytic properties of the zirconocenes were investigated in propene polymerisations. X-ray analysis has been used for zirconocene structure confirmation.Figure optionsDownload as PowerPoint slide