Towards the nature of active sites in polymerization of cyclic esters initiated by aluminium alkoxides: First structurally authenticated aluminium-ε-caprolactone complex

Abstract

The isolation and structural characterization of a methylaluminium(bisphenoxide)-ε-caprolactone complex is reported. While the three-coordinate methylaluminium complex was found not to catalyze the polymerization of ε-caprolactone, its oxygenation led to the formation of an aluminium methoxide compound, which appeared to be a very good initiator. The relative propensity of the Al-X bonds for monomer insertion in the initial step of polymerization is also discussed.