The reaction of ZnEt₂ with one or two equivalents of aminophenolate ligand N-[methyl(2-hydroxy-3,5-di-tert-butylphenyl)]-N-methyl-N-cyclohexylamine gives hetero- and homoleptic molecular compounds [(μ,η²-L²)ZnEt]₂ and [Zn(η²-L²)₂]. The later is most probably a mixture of diastereoisomers that in solution shows an interesting dynamic behaviour. Both complexes as well as the BnOH derivative of the latter, [(η²-L²)Zn(μ-BnO)]₂, proved excellent initiators for lactide polymerization.

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.