Bimetallic nickel and cobalt complexes as high-performance catalysts for copolymerization of carbon dioxide with cyclohexene oxide

Abstract

New bimetallic nickel, cobalt and zinc complexes bearing a bis(benzotriazole iminophenolate) ligand and ancillary acetate groups were developed for CO₂/epoxide copolymerization. Ni and Co complexes are active catalysts for the copolymerization of cyclohexene oxide (CHO) and CO₂ without co-catalysts. Particularly, well-defined di-Ni 1 was found to effectively copolymerize CHO with CO₂, giving copolymers with a high molecular weight and a high carbonate linkage content. This is the first example of a dinuclear nickel acetate complex that is efficient for CO₂/CHO copolymerization as well as for the formation of highly alternative poly(cyclohexene carbonate) in a controllable manner.