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

摘要

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)(2)N)(2)Nd(mu'-Cl)(2)Li(THF)(3)}(mu-Cl)](2) (1), [{((Me3Si)(2)N)(2)Ln(mu'-Cl)Li(THF)(2)}(mu(3)-Cl)](2) (Ln = Eu (2); Ln = Ho (3)), and [{(Me3Si)(2)NLn(mu'-Cl)(2)Li(THF)(2)}(mu-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)(2)NLn(mu'-Cl)(2)Li(THF)(2)}(mu-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)(2)N)(2)Ln(mu'-Cl)Li(THF)(3)}(mu-Cl)](2) (Ln = Nd (1); Sin (9)) [{((Me3Si)(2)N)(2)Ln(mu'-Cl)Li(THF)(2)}(mu(3)-Cl)](2) (Ln = Sin (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 E-caprolactone. (C) 2004 Elsevier B.V. All rights reserved.