Synthesis and characterization of lanthanide complexes stabilized by N-aryl substituted β-ketoiminato ligands and their application in the polymerization of rac-lactide

Abstract

Several lanthanide complexes supported by N-aryl substituted β-ketoiminato ligands were synthesized by the protonolysis reaction. Reactions of 1-phenyl-3-N-(p-methoxyphenylimino)-1-butanone (HL) with Ln[N(SiMe3)2]3 and Ln(OAr)3(THF) (ArO = 2,6-But2-4-MeC6H2O) in a 2:1 M ratio gave mononuclear lanthanide amides L2Ln[N(SiMe3)2] [Ln = Y (1), Sm (2), Nd (3)] and aryloxides L2Ln(OAr) [Ln = Y (4), Nd (5)], respectively, whereas the same reaction with Yb[N(SiMe3)2]3 afforded an unexpected homoleptic ytterbium complex L3Yb (6). The solid-state structures of lanthanide complexes 1–6 were determined by single-crystal X-ray diffraction. It was found that complexes 1–5 can efficiently initiate the ring-opening of rac-lactide in THF to afford hetereotactic-rich polylactides.