Phongnarin ChumsaengSetsiri HaesuwannakijSareeya BureekaewVuthichai ErvithayasupornSupawadee NamuangrukKhamphee PhomphraiVidyasirimedhi Institute of Science and TechnologyMahidol UniversityThailand National Science and Technology Development Agency2019-08-232019-08-232018-08-20Inorganic Chemistry. Vol.57, No.16 (2018), 10170-101791520510X002016692-s2.0-85051865547https://repository.li.mahidol.ac.th/handle/20.500.14594/45481Copyright © 2018 American Chemical Society. Polymerizations of biodegradable lactide and lactones have been the subjects of intense research during the past decade. They can be polymerized/copolymerized effectively by several catalyst systems. With bis(phenolate)-amine aluminum complex, we have shown for the first time that lactide monomer can deactivate the aluminum complex during the ongoing polymerization of ϵ-caprolactone to a complete stop. After hours of dormant state, the aluminum complex can be reactivated again by heating at 100 °C without the addition of any external chemicals still giving polymer with narrow dispersity. Studies using NMR, in situ FTIR, and single-crystal X-ray crystallography indicated that the coordination of the carbonyl group in lactyl unit was responsible for the unusual behavior of lactide. In addition, the unusual methyl-migration from methyl lactate ligand to the amine side chain of the aluminum complex was observed through intermolecular nucleophilic-attack mechanism.Mahidol UniversityChemistryArticleSCOPUS10.1021/acs.inorgchem.8b01364