title: Highly efficient magnesium initiators for lactide polymerization.
abstract: Two monomeric, six-coordinated magnesium complexes with bulky aminophenolate ligands [(Htbpoa)2Mg] (1) and [(Htbpca)2Mg(THF)2] (2), where Htbpoa =N-[methyl(2-hydroxy-3,5-di-tert-butylphenyl)]-N-methyl-N-methyl-1,3-dioxolaneamine and Htbpca =N-[methyl(2-hydroxy-3,5-di-tert-butylphenyl)]-N-methyl-N-cyclohexylamine have been prepared, characterized and employed as initiators for lactide polymerization. The crystal structure of the homoleptic compound 1 has been determined and shows that the six-coordinate magnesium atom in 1 is surrounded by two tridendate tbpoa ligands. In the solution, however, complex 1 exists in equilibrium with a five-coordinate species 1a having one oxolane fragment dangling. The tbpoa and tbpca ligands in 1 and 2 play a dual role, as the ancillary ligand stabilizing the monomeric magnesium species and as the initiating polymerization group.
authors.affiliation: Faculty of Chemistry, University of Wroclaw, 14, F. Joliot-Curie, 50383 Wroclaw, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Ejfler
authors.forename: Michał
authors.initials: M
authors.lastname: Kobyłka
authors.forename: Lucjan B
authors.initials: LB
authors.lastname: Jerzykiewicz
authors.forename: Piotr
authors.initials: P
authors.lastname: Sobota