Di- and trinuclear zirconium complexes as catalysts for ethylene polymerization

•Di- and trinuclear zirconium complexes.•Bis(phenoxyimine)zirconium complexes.•Sonogashira coupling reactions.•Activation with methylaluminoxane (MAO).•Catalytic ethylene polymerization.

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.

Graphical abstractDi- and trinuclear zirconium complexes can be activated with methylaluminoxane (MAO) in solution for catalytic ethylene polymerization. The polymers have bi- or multimodal molecular weight distributions.Figure optionsDownload full-size imageDownload as PowerPoint slide