Dimeric 5-and 6-coordinate complexes of tri and tetradentate ligands

Abstract

Orthohydroxyacetophenone-picolinoylhydrazone (APH) and orthohydroxy-acetophenone-isonicotinoly hydrazone (AIH) react with divalent nickel and cobalt salts in methanolic medium and give complexes of the type [M(APH)X] 2 and [M(AIH)X] 2 where MNi(II) and Co(II), XCl, Br, NO 3, NCS or H 2O, depending upon the pH of the reaction mixture. The compounds are characterised by elemental analyses, conductance, molecular weight, magnetic, electronic and IR (including far. IR) spectral studies. The ligands act as tetra (APH) and tri (AIH)-dentate, conforming to 6 or 5-coordinate geometries at low and high pH. The IR spectral studies, molecular weight determination and subnormal values of magnetic moments indicate the dimeric nature of these complexes. The electronic spectra are consistent with the proposed stereochemistries. The complexes, however, have lower symmetries and the amount of distortion in terms of DT/DQ, applying NSH “Hamiltonian Theory” has been evaluated which indicate that the complexes are moderately distorted.