provided are novel dinuclear indium catalysts of formula that are capable of living and immortal ring opening polymerization and copolymerization of cyclic ester monomers for the preparation of biodegradable polymers and copolymers , in particular polyesters . also disclosed are polymerization methods and polymer products . these dinuclear indium catalysts allow less costly , highly reactive living polymerization of cyclic ester monomers with possible high turn over rates and / or substantial stereo chemical and microstructure control .