Metallocene catalysts covalently tethered on silica surfaces

A group 4 metallocene complex that serves as olefin polymerization catalyst was tethered on a solid support such as silica gel by covalent bonds. A zirconocene complex that has a vinyl group on its cyclopentadienyl ligand was hydrosilated or hydroborated to introduce a functional anchor for immobilization reactions. The complex with a Si-Cl group was tethered on a silica surface by the reaction with a surface Si-OH group. The zirconocene with a BH group was immobilized on a silica gel modified with chlorodimethylvinylsilane. Ethylene polymerization using the tethered catalysts, showed that the hydroboration-method seems more effective than the hydrosilation-method, It exhibited comparable catalytic activity to the corresponding homogeneous catalyst and produced polyethylene of a higher molecular weight.