Catalytic copolymerization of epoxides with phthalic anhydride or carbon dioxide by effective binuclear zinc and nickel complexes: Catalysis and kinetics

Novel bimetallic zinc(II) and nickel(II) complexes based on benzothiazole-containing diamine-bisphenolate ligands have been developed as effective catalysts for the ring-opening copolymerization (ROCOP) of epoxides with phthalic anhydride (PA) or carbon dioxide (CO2). The catalytic results revealed that all dizinc(II) complexes can serve as active catalysts for ROCOP of PA and cyclohexene oxide (CHO). Dizinc(II) complex 3, supported by 2,4-dinitrophenolate coligands, exhibited the best catalytic activity. Moreover, these nickel(II) complexes were found to be effective catalysts for the alternating copolymerization of carbon dioxide with CHO; dinickel(II) complex 5, coordinated on bromide ion, showed excellent catalytic performances. Kinetic studies of ROCOP for two different types by complex 3 or 5 further indicate a zero-order dependence on the concentration of PA and CO2, and a first-order dependence on the concentration of CHO and the corresponding catalyst.