PREPARATION AND PROPERTIES OF COMPLEXES OF LANTHANIDE(III) SALTS WITH N-(2-PYRIDYL) PYRIDINE-2'-CARBOXAMIDE

New complexes of the general formulae [Ln(LH)2(NCS)3(H2O)] (Ln = La-Eu), [Ln(LH)2(NCS)3] (Ln = Gd-Yb), [Ln(LH)3(OClO3)](ClO4)2 (Ln = La-Gd), [Ln(LH)3] (ClO4)3 (Ln = Tb-Yb), [Ln(LH)2(ONO2)2](NO3) (Ln = La-Yb) and [Ln(LH)(ONO2)3] (Ln = La, Pr, Nd, Sm, Eu), where LH = N-(2-pyridyl)pyridine-2'-carboxamide, have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, X-ray powder patterns, thermal methods, magnetic susceptibilities and spectroscopic (IR, H-1 NMR, electronic diffuse reflectance and solid state emission f-f spectra) studies. All the data are discussed in terms of the nature of the bonding and the possible structural types. The 1:2 and 1:3 complexes appear to be monomeric, while polymeric structures are assigned for the 1:1 nitrato compounds. The LH molecule behaves as a bidentate ligand in the monomeric complexes, bonding through the amide oxygen and N(1'). The amide oxygen and both pyridine residues are coordinated in the 1:1 nitrato complexes.