Di- and trinuclear zirconium complexes as catalysts for ethylene polymerization

Abstract

Bimodal and multimodal molecular weight distributions of polyethylenes can be achieved with di- or trinuclear zirconium catalysts in homogeneous solution. In order to prepare such complexes, bis(phenoxyimine) zirconium complexes and zirconocene complexes were coupled in Sonogashira reactions. Hydrosilylation reactions were applied for the combination of metallocene complexes with silane substituted N-heterocyclic compounds, such as 3,5-dimethylpyrazoles. The resulting di- and trinuclear complexes were activated with methylaluminoxane (MAO) and applied as catalysts for ethylene polymerization. The catalytic performances of these complexes and their applications in olefin polymerization reactions are discussed.