Synthesis, characterization and l-lactide polymerization behavior of rare-earth metal bis(silylamide) complexes supported by arylamido ligand

•Mono(arylamido) rare-earth metal bis(silylamide) complexes were synthesized.•Mono(arylamido) rare-earth metal bis(silylamide) complexes were active for l-lactide polymerization.•Mono(arylamido) rare-earth metal bis(silylamide) complexes were characterized.

Salt metathesis of LnCl3, [2,6-iPr2C6H3N(SiMe3)]Li and LiN(SiHMe2)2 in 1:1:2 molar ratio in THF produced the mono-arylamido-ligated rare-earth metal bis(silylamide) complexes [2,6-iPr2C6H3N(SiMe3)]Ln[N(SiHMe2)2]2(THF) (Ln = Y (1), Lu (2), La (3)) in good isolated yields. All these complexes were characterized by elemental analysis, NMR spectroscopy and FT-IR spectroscopy. 1 was further structurally authenticated by single crystal X-ray diffraction. These complexes alone could serve as highly active initiators for l-lactide polymerization in toluene at 50 °C. Employing 1 as the initiator, l-lactide polymerization proceeded in a controllable fashion via the coordination-insertion mechanism verified by end group analysis of the oligomer.

Graphical abstractThe mono-arylamido-ligated rare-earth metal bis(silylamide) complexes [2,6-iPr2C6H3N(SiMe3)]Ln[N(SiHMe2)2]2(THF) (Ln = Y, Lu, La) were prepared and they could serve as highly active initiators for l-lactide polymerization.Figure optionsDownload full-size imageDownload as PowerPoint slide