β-Diketiminate and β-Ketoiminate Metal Catalysts for Ring-Opening Polymerization of Cyclic Esters

This review highlights the ongoing developments on the ring-opening polymerization (ROP) of lactide (LA) and caprolactone (CL) using mononuclear and dinuclear β-diketiminate- and β-ketoiminate-substituted metal complexes. The resulting aliphatic polyesters are of great interest as sustainable replacements to petrochemicals-based polymers with potential applications in tissue engineering, bio-medical, and agricultural sciences. β-Diketiminate and β-ketoiminate metal complexes are very promising ROP catalysts since their steric and electronic properties, and hence their catalytic activity and selectivity can be easily modified. This review compares different classes of β-diketiminate and β-ketoiminate complexes with respect to the controlled synthesis of homopolymers and copolymers of aliphatic polyesters and elaborates on the polymerization kinetics and mechanistic studies.