Dilithium Complex Incorporating Phenyl Bridged Neutral Pyrrolyl-Arylamide Ligand: Synthesis, Characterization, Reaction, and Catalytic Activity

The phenyl bridged neutral pyrrolyl-arylamide ligand with the formula 2-(2, 5-Me2C4H2N)C6H4NHSiMe3 (HL) was synthesized and characterized. Treatment of the ligand HL with equivalent of nBuLi or LiCH2SiMe3 afforded the lithiated complex [η5:(μ-η1:η1)-2-(2,5-Me2C4H2N)C6H4NSiMe3Li]2 (1) smoothly in good yield. The reaction of complex 1 with two equivalents of ErCl3(thf)3.5 and LiCH2SiMe3 produced novel trinuclear erbium-lithium cluster [η5:η1:(μ-η1:η1)-2-(2,5-Me2C4H2N)C6H4NSiMe2CH2ErCl]2LiCl(thf)2 (2) through sp3 C-H bond activation of methyl group and the resulting methylene group bonding two erbium centers in a rare μ2-η1:η1 mode. In addition, the dilithium complex 1 exhibited a high catalytic activity toward ring-opening polymerization of ε-caprolactone.