Synthesis and Spectral Studies of Some Lanthamide Metal Chelates of an Unsymmetrical Tridentate Schiff-Base

Abstract

A series of trivalent lanthanide metal complexes of the type [Ln(Hanh)₂Cl(H₂O)Cl₂.2H₂O (where Ln = La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III) and Y(III), and Hanh = acetonenicotinoyl hydrazone), have been synthesized by the direct reaction of acetonenicotinoyl hydra-zone with hydrated lanthanide(III) chlorides in an ethanol -acetone mixture. The complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, I. R., NMR and emission spectral techniques. Several bonding parameters and oscillator strengths have been calculated from the absorption spectra of Pr(III), Nd(III), Sm(III) and Dy(III) complexes. [Nd(Hanh)₂Cl(H₂O)]cl₂.2H₂O has been studied for its oscillator strength variation with temperature and pH. IR and NMR spectral data suggest the non-deprotonated tridentate nature of Hanh in the eight-coordinated complexes. The intensity ratio (η) has been calculated from the emission spectrum of the Tb(III) complex.