Zinc N-heterocyclic carbene complexes and their polymerization of d,l-lactide

Authors

Tryg R. Jensen
Chris P. Schaller, College of Saint Benedict/Saint John's UniversityFollow
Marc A. Hillmyer
William B. Tolman

Document Type

Article

Publication Date

12-2005

Disciplines

Chemistry | Physical Sciences and Mathematics

Abstract

A series of zinc complexes of monodentate N-heterocyclic carbenes (NHCs) and a new sterically bulky bidentate pyridyl-NHC ligand have been synthesized and characterized by spectroscopic and X-ray crystallographic methods. Dinuclear alkoxide complexes of monodentate NHC complexes with 2,4,6-trimethylphenyl substituents appear to form monomeric species in solution and show good control and activity for lactide polymerization, including mild stereoelectivity as indicated by formation of heterotactic-enriched polylactide in d,l-lactide polymerizations. Kinetics studies revealed an overall second order rate law, first order in [LA] and [catalyst]. Efforts to obtain Zn–alkoxide complexes of a more sterically hindered NHC with 2,6-diisopropylphenyl groups were unsuccessful due to Zn–NHC bond scission. Ligand dissociation was also observed in attempts to prepare Zn–alkoxide complexes of the bidentate pyridyl-NHC system, despite its chelating nature.

Comments

DOI: 10.1016/j.jorganchem.2005.07.070

This article belongs to a special issue: "Carbene Chemistry," edited by G. Bertrand.

Recommended Citation

Jensen, T. R.; Schaller, C. P.; Hillmyer, M. A.; Tolman, W. B. Zinc N-heterocyclic carbene complexes and their polymerization of d,l-lactide. Journal of Organometallic Chemistry, 2005, 690(24-25), 5881-5891.