High-Activity and High-Selectivity Air-Stable Nickel and Copper Complexes for Copolymerization of Epoxides with Anhydrides

Ring-opening copolymerization (ROCOP) of epoxides with anhydrides presents a highly promising pathway for the synthesis of diverse polyester copolymers. This process involves the simultaneous opening of the epoxide ring and the anhydride ring, resulting in the formation of copolymer chains with alternating repeating units. Here, we synthesized a series of nickel and copper complexes coordinated by amine-bis(benzotriazole phenolate) ligands (^C1NNBiBTP-H₂). Different acid-base conditions can result in the synthesis of diverse coordination structures. The six-coordinated mononuclear Ni catalyst synthesized in this study exhibited competitive turnover frequencies (TOF = 450 h^-1) compared to previous studies involving copolymerization of epoxides with anhydrides. This indicates the catalyst's high activity in facilitating the copolymerization reaction. The results indicate that the catalyst exhibited a high molecular weight control ability and high polymer selectivity for the ROCOP of epoxides and anhydrides. Thus, this air-stable catalyst has the potential for use in industries.