Synthesis and structural characterization of the lanthanide Schiff-base complexes {[CH2CH2N=CH(2-O-3,5-t-Bu2C6H2)](3)}Ln (Ln = Sm, Nd)

Reaction of LnEN(SiMe3)(2)](3) (Ln=Sm, Nd) with one equivalent of the bulky heptadentate Schiff-base ligand N[CH2CH2N=CH(2-OH-3,5-t-Bu2C6H2)(3), (1) r esulted in formation of the 7-coordinate complexes {N[CH2CH2N=CH(2-O-3:5-t- Bu2C6H2)](3)}Ln (Ln = Sm (2), Nd (3)). X-ray diffraction studies of 2 and 3 reveal isostructural hemi-toluene solvate complexes in which the N4O3 dono r atom set of the ligand defines a slightly distorted capped octahedral geo metry about the metal center. Ln-N bond lengths are of two types - an avera ge of 2.556(3) Angstrom (2) (2.587(5) Angstrom (3)) to the three imine nitr ogens, and a significantly longer interaction of 2.818(4) Angstrom (2) (2.8 11(5) Angstrom (3)) with the apical amine nitrogen. Ln-O distances lie in t he range 2.218(3)-2.232(4) Angstrom for 2 and 2.241(6)-2.248(4) Angstrom fo r 3. (C) 2001 Published by Elsevier Science B.V. All rights reserved.