Synthesis, Reactivity, and Characterization of Amine Bis(phenolate) Lanthanide Complexes and Their Application in the Polymerization of ε-Caprolactone

A series of amine bis(phenolato)lanthanide methyl and amido complexes were synthesized by general salt metathesis reaction in this paper. The reaction of anhydrous lanthanide trichlorides with 1 equiv of sodium amine bis(phenolate) LNa 2 [L = Me 2 NCH 2 CH 2 N{CH 2 -(2-O-C 6 H 2 -Bu t 2 -3,5)} 2 ] in THF at room temperature gave the amine bis(phenolate) lanthanide chlorides LLnCl(THF) (Ln = Yb ( 1 ), Ln = Er ( 2 )). Complexes 1 and 2 can be used as starting materials to prepare amine bis(phenolate) lanthanide derivatives. Complexes 1 and 2 reacted with lithium methyl and lithium amide, respectively, to give the corresponding lanthanide methyl and amido products LLnMe(THF) (Ln = Yb ( 3 ), Ln = Er ( 4 )) and LLnNPh 2 (THF) (Ln = Yb ( 5 ), Ln = Er ( 6 )). These complexes were well characterized by elemental analyses and IR spectra. The definitive molecular structures of complexes 1, 2, 3, 5, and 6 were provided by single-crystal X-ray analyses. Reactivity studies of complexes 3, 5, and 6 have shown them to be efficient initiators for the ring-opening polymerization of ε -caprolactone.