Studies on 3d Metal Complexes of N²-Ethoxythiocarbonyl Benzoic Acid Hydrazide and N²-Ethoxythiocarbonyl Pyridine-4-carboxylic Acid Hydrazide⁺

Abstract

The ligands H₂etbh [C₂H₅OC(S)NH-NH-C(O)C₆H₅] and H₂etph [C₂H₅OC(S)NHNHC(O)C₅H₄N] form 1:2 metal-ligand deprotonated complexes with Mn(II) and Fe(II) and 1:1 deprotonated complexes with Co(II), Cu(II), and Zn(II), Ni(II), however, forme 1:1 complex with H₂etbh and 1:2 complex with H₂etph. The complexes have been characterized by elemental analysis and physico-chemical measurements. The 1:2 complexes are very slightly soluble in DMF and DMSO while others are insoluble in water as well as common organic solvents. Magnetic and electronic spectral studies suggest a square-planar geometry for the Ni(etbh) and Cu(II) complexes; an octahedral geometry for the Ni(Hetph)₂ and Fe(II) complexes and a tetrahedral geometry for the Co(II) complexes. ESR spectra of the Cu(II) complexes suggest that the unpaired electron is present in the d_x²-y² orbital of Cu(II). IR spectral studies indicate that the ligands are uninegative tridentate in their 1:2 complexes and binegative tetradentate in 1:1 complexes. Based on analytical and physico-chemical data, structures of the complexes have been proposed.