Syntheses, crystal structures and catalytic properties of a series of lanthanide(III) bis(trimethylsilyl)amide chloride complexes: [{((Me3Si)2N)2Nd(μ′-Cl)Li(THF)3}(μ-Cl)]2, [{((Me3Si)2N)2Ln(μ′-Cl)Li(THF)2}(μ3-Cl)]2 (Ln = Eu, Ho), and [{(Me3Si)2NLn(μ′-Cl)2

Reactions of anhydrous lanthanide(III) trichloride (Ln = Nd, Sm, Eu, Ho, Yb) with one or two equiv. of LiN(SiMe3)2 in THF produced a family of lanthanide(III) bis(trimethylsilyl)amide chloride complexes: [{((Me3Si)2N)2Nd(μ′-Cl)Li(THF)3}(μ-Cl)]2 (1), [{((Me3Si)2N)2Ln(μ′-Cl)Li(THF)2}(μ3-Cl)]2 (Ln = Eu (2); Ln = Ho (3)), and [{(Me3Si)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 [{(Me3Si)2NLn(μ′-Cl)2Li(THF)2}(μ-Cl)]2 (Ln = Nd (4); Sm (5); Eu (6); Ho (7)) with 2 equiv. of LiN(SiMe3)2 in THF afforded the corresponding disubstituted complexes [{((Me3Si)2N)2Ln(μ′-Cl)Li(THF)3}(μ-Cl)]2 (Ln = Nd (1); Sm (9)), [{((Me3Si)2N)2Ln(μ′-Cl)Li(THF)2}(μ3-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.