Syntheses, crystal structures and catalytic properties of a series of lanthanide(III) bis(trimethylsilyl)amide chloride complexes: [{((Me 3Si) 2N) 2Nd(μ′-Cl)Li(THF) 3}(μ-Cl)] 2, [{((Me 3Si) 2N) 2Ln(μ′-Cl)Li(THF) 2}(μ 3-Cl)] 2 (Ln = Eu, Ho), and [{(Me 3Si) 2NLn(μ′-Cl) 2Li(THF) 2}(μ-Cl)] 2 (Ln = Nd, Sm, Eu, Ho, Yb)

Abstract

Reactions of anhydrous lanthanide(III) trichloride (Ln = Nd, Sm, Eu, Ho, Yb) with one or two equiv. of LiN(SiMe 3) 2 in THF produced a family of lanthanide(III) bis(trimethylsilyl)amide chloride complexes: [{((Me 3Si) 2N) 2Nd(μ′-Cl)Li(THF) 3}(μ-Cl)] 2 ( 1), [{((Me 3Si) 2N) 2Ln(μ′-Cl)Li(THF) 2}(μ 3-Cl)] 2 (Ln = Eu ( 2); Ln = Ho ( 3)), and [{(Me 3Si) 2NLn(μ′-Cl) 2Li(THF) 2}(μ-Cl)] 2 (Ln = Nd ( 4); Ln = Sm ( 5); Ln = Eu ( 6); Ln = Ho ( 7); Ln = Yb ( 8)). On the other hand, reactions of the monosubstituted silylamido complexes [{(Me 3Si) 2NLn(μ′-Cl) 2Li(THF) 2}(μ-Cl)] 2 (Ln = Nd ( 4); Sm ( 5); Eu ( 6); Ho ( 7)) with 2 equiv. of LiN(SiMe 3) 2 in THF afforded the corresponding disubstituted complexes [{((Me 3Si) 2N) 2Ln(μ′-Cl)Li(THF) 3}(μ-Cl)] 2 (Ln = Nd ( 1); Sm ( 9)), [{((Me 3Si) 2N) 2Ln(μ′-Cl)Li(THF) 2}(μ 3-Cl)] 2 (Ln = Sm ( 9), Eu ( 2); Ho ( 3)). These complexes were characterized by melting point determination, elemental analysis and IR spectra. Single-crystal X-ray diffraction studies revealed that these compounds are chloride-bridged dimers, in which Ln metals in 1– 3 display a distorted trigonal bipyramidal coordination geometry while those in 5, 6 and 8 a distorted octahedral coordination geometry. Complexes 1– 9 exhibited catalytic activity for the ring-opening polymerization of ε-caprolactone.