The salt-free diamido complexes of lanthanide supported by β-diketiminate: Synthesis, characterization, and their catalytic activity for the polymerization of acrylonitrile and ε-caprolactone

The synthesis and structure of the salt-free diamido complexes of lanthanide supported by β-diketiminate ligand (2,6-Me2C6H3)NC(Me)CHC(Me)N(2,6-Me2C6H3) are described. The β-diketiminate lanthanide dichloride LLnCl2(THF)2 (L = N,N′-bis(2,6-dimethylphenyl)-2,4-pentanediiminate) [Ln = Yb (1), Nd (2)] was prepared by the metathesis reaction of LLi with anhydrous LnCl3 in a 1:1 molar ratio in THF at room temperature. Reactions of 1 and 2 with 2 equiv. of LiNPh2 in THF gave the salt-free complex LLn(NPh2)2(THF) [Ln = Yb (3), Nd (4)] in good yield as crystalline solids. Both compounds were characterized crystallographically. The coordinated geometry around the central metal can be described as a distorted trigonal bipyramid. Complexes 3 and 4 showed good catalytic activity for the polymerization of acrylonitrile and high activity for the ring-opening polymerization of ε-caprolactone at room temperature.