Coordination behaviour of pyridoxalisonicotinoyl hydrazone towards some 3d-metal ions

Abstract

The complexes of divale t manganese, cobalt, nickel, copper, zinc and the ligand pyridoxalisonicotinoyl hydrazone (PIH) are discussed in order to illustrate the behaviour of the ligand towards the metal ions in acidic and neutral media. The complexes [M(PIH-2H)(H2O)3](M = Mn, Co and Zn), [cu(pih-2h)(h2O)2]2, [cu(pih)c1(H2O)]2 2+ and [Ni(PIH)Cl2(H2O)] have distorted octahedral structures. The isostructural crystalline complexes, [m(pih)c12]2 (M= Mn, Co andZn) are isolated from hot solutions. The electronic spectral data of cobalt in conjunction with infrared, NMR and magnetic measurements enables the assignment of the formula [m(pih) 2][MC14] to these complexes. The anion is tetrahedral while the cation has an octahedral chromophore. Characterization data indicates that [Ni(PIH-2H)H2O] has a four-coordinated square-planar chromophore. The IR, and 1H 13 C NMR spectral data indicate that PIH behaves as a neutral tridentate ligand in the chloro complexes and as a dinegative, tridentate species in the deprotonated complexes. © 1992, Taylor & Francis Group, LLC. All rights reserved.