Ring-Opening Copolymerization of Epoxides with Cyclic Anhydrides Promoted by Bimetallic and Monometallic Phenoxy–Imine Aluminum complexes

Two dinuclear aluminum alkyl complexes bearing a salen ligand with alkyl backbone of different length between the nitrogen atoms (1,3-propylene and 1,5-pentylene backbone) and the related hemisalen aluminum complex were tested as catalysts in the ring-opening copolymerization of cyclohexene oxide and limonene oxide with succinic anhydride and phthalic anhydride. The effects of different reaction conditions (co-catalyst and solvent) on the productivity and selectivity of the reactions were evaluated. The comparison of the catalytic behavior of the dinuclear complexes bearing the aluminum reactive centers at different distances as well as of their mononuclear counterpart suggested that the copolymerization follows a monometallic pathway differently from what was observed in the homopolymerization of CHO.