Reaction of Coordinated Ligands. I. Synthesis and Characterization of Some Lanthanide Complexes of 2,6-diacetylpyridine-2-thenoylisonicotinoyl Dihydrazone

Abstract

Reaction of [Ln(Hdapth)Cl₂(H₂O)₃]Cl [Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy; Hdapth = 2,6-diacetylpyridine mono(2-thenoylhydrazone)] with isonicotinoylhydrazine (inn) in ethanol yielded complexes of the type [Ln(H₂dapthinh)Cl(H₂O)₂]Cl₂ (H₂dapthinh = 2,6-diacetylpyridine-2-thenoyl isonicotinoyl dihydrazone). Their chemical compositions have been established from analytical, molar conductance and FAB mass data. The results of IR and NMR spectral data indicated pentadentate bonding of 2,6-diacetylpyridine-2-thenoyl isonicotinoyl dihydrazone (H₂dapthinh) to the metal ions. The electronic spectral data have been used to calculate the various spectral parameters viz. nephelauxetic ratio (β), bonding (b^1/2). Sinha (δ%), covalency (η) and oscillator strength (P). The shape and positions of the hypersensitive transition in the Nd(III) complex indicated the coordination number eight around the Nd³¹ion. The symmetry of the ligand field around the metal ions is indicated from the emission spectra.