Novel binuclear manganese(III), cobalt(III) and chromium(III) complexes for the alternating ring-opening copolymerization of cyclohexene oxide and maleic anhydride

Several unsymmetrical Schiff-base mononuclear and binuclear manganese(III), cobalt(III) and chromium (III) complexes have been designed, synthesized and applied to the alternating ring-opening copolymerization of cyclohexene oxide and maleic anhydride with the optimized conditions. Experimental results show that these complexes are effective in the catalytic copolymerization. Among the six complexes, the binuclear complexes exhibited better catalytic activity than mononuclear complexes under the same conditions. The highest molecular weight (24,600 g mol(-1)) of copolymer with a narrow polydispersity (1.07) and higher conversion of the monomer (95%) were achieved when using binuclear chromium (III) complex, followed by the manganese(III) complex and the cobalt(III) complex showed relatively lower activity at the same conditions. It is due to maybe existed an intramolecular bimetallic synergistic effect in the binuclear catalysts system different from the mononuclear catalysts system. (C) 2016 Elsevier B.V. All rights reserved.