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

• Higher catalytic activity of binuclear complexes based on asymmetrical Schiff-base ligand.
• Intramolecular bimetallic synergistic effect in the binuclear catalysts system.
• Polyester with perfectly alternating copolymerization structure.

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.

Several unsymmetrical Schiff-base mononuclear and binuclear manganese(III), cobalt(III) and chromium(III) complexes have been obtained and binuclear complexes showed higher catalytic activity in CHO-MA bulk or solution ring-opening copolymerization under the optimal conditions.Figure optionsDownload as PowerPoint slide