Dinuclear vs. mononuclear complexes: accelerated, metal-dependent ring-opening polymerization of lactide

Dinuclear complexes of aluminum and indium with a bis(phenoxy-imine) platform have been synthesized and used in the polymerization of lactide. Kinetic studies demonstrate that the dialuminum precursor provides a more favorable reaction pathway in terms of activation free energy than that of directly related monoaluminum systems. No similar trend is observed with the corresponding diindium–monoindium systems, which is attributed to a dissimilar ROP mechanism.