Developments in Binuclear α-Diimine Nickel Catalysts for Ethylene Polymerization

Binuclear α-diimine nickel catalysts have attracted significant interest in ethylene polymerization due to their distinctive metal–metal cooperativity, which enables catalytic properties not achievable with mononuclear systems. This review summarizes the structural design principles and recent advances of these binuclear catalysts, with an emphasis on how different bridging architectures such as rigid aryl, flexible chain, N-heterocyclic, and specialty bridges regulate intermetallic distance, steric environment, and electronic effects. The impact of these structural factors on catalytic activity, polymer molecular weight, branching density, and mechanical properties is discussed. By establishing structure–performance relationships, this review provides a foundation for the rational design of binuclear nickel catalysts for advanced polyethylene synthesis.