Iron complexes containing N-heterocyclic carbene ligands were utilized for the polymerization of (rac)-lactide and other cyclic diesters. Compared to related bis(imino)pyridine iron complexes, iron complexes containing bis(amidinato)-N-heterocyclic carbene ligands demonstrated different activities and the ability to achieve high molecular weight polymer (Mn> 20,000 g/mol) while maintaining characteristics of a living polymerization reaction. The different activity for these catalysts is presumably due to the electron donating characteristics inherent to N-heterocyclic carbene ligands in comparison to pyridine ligands. Influence of the alkoxide initiator, the identity of the ancillary ligand, the oxidation state of the metal, and the identity of the monomer will be presented.

Application of N-heterocyclic carbene�iron complexes for the polymerization of cyclic diesters

248th National Meeting (2014)

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