Zinc complexes containing coumarin-derived anilido-aldimine ligands as catalysts for ring opening polymerization of L-lactide.

The coumarin-derived ligand precursors L(1)H-L(6)H have been prepared. Treatment of these ligand precursors with 1.2 equiv. of ZnEt2 in toluene affords zinc ethyl complexes (LZnEt) 1-6 (where L = coumarin-derived ligands bearing different functional groups). Reaction of ligand precursor L(3)H with 1.5 equiv. of Zn[N(SiMe3)2]2 in toluene affords the zinc amide complex, L(3)ZnN(SiMe3)2, 7. All these compounds were characterized by NMR spectroscopy and elemental analysis. The molecular structures are reported for 1 and 7. The catalytic activities of complexes 1-7 towards the ring opening polymerization of l-lactide in the presence of 9-AnOH have been investigated.