N-HETEROCYCLIC CARBENE BASED ZIRCONIUM COMPLEXES FOR USE IN LACTONES RING OPENING POLYMERIZATION

摘要

This invention is reporting new N-heterocyclic carbene based zirconium (or hafnium) complexes and their uses as catalysts for the lactones ring opening polymerization. These new catalysts are robust and versatile and exert control over polymer molecular weight and/or stereochemistry and exhibit high reactivity (cf. for low temperature applications). In particular the new catalysts show both enhanced activity and at the same time a better selectivity than the catalysts employed by the prior art.