Di-magnesium and zinc catalysts for the copolymerization of phthalic anhydride and cyclohexene oxide

Two new homogeneous dinuclear catalysts for the ring-opening copolymerization of phthalic anhydride (PA)/cyclohexene oxide (CHO) and the terpolymerization of phthalic anhydride (PA)/cyclohexene oxide (CHO)/carbon dioxide (CO 2 ) are reported. The catalysts are a di-magnesium ( 1 ) and a di-zinc complex ( 2 ), both are coordinated by the same macrocyclic ancillary ligand. Both catalysts show good polymerization control and activity (TOF = 97 ( 1 ) and 24 ( 2 ) h −1 ), with the di-magnesium complex ( 1 ) being approximately four times faster compared to the di-zinc ( 2 ) analogue. Their relative reactivity is closely related to that observed for well documented chromium salen/porphyrin catalysts. However, these results represent the first example of a well-defined magnesium catalyst which may be advantageous in terms of obviating use of co-catalysts, low cost, lack of colour and redox chemistry.