Cobalt(II) and nickel(II) complexes of hydrazone ligand ({(1E)-1-aza-2-pyrrol-2-ylvinyl}{5,6-diphenyl(1,2,4-triazin-3-yl)}amine): Synthesis, spectral, pH metric, antimicrobial and PM3 studies

Abstract

Binary and ternary complexes have been synthesized by reaction of the hydrazone ligand, (HL) with cobalt(II) nitrate and nickel(II) nitrate in absence and presence of second ligands. The new complexes have been characterized by elemental and thermal analyses, conductivity and magnetic susceptibility measurements as well as IR, UV-visible, ESR and mass spectra. The binary complexes have tetrahedral geometry, but ternary complexes have square planar, square pyramidal and octahedral geometries. The ligand acts as a monobasic tridentate and bidentate donor, for binary and ternary complexes, respectively. The pH metric studies at different temperature are used to calculate stepwise stability constants and thermodynamic parameters of Co(II) and Ni(II) complexes in 75 % (v/v) dioxane-water. The hyperchem 7.52 program utilized to determine the optimized structures of the ligand and its complexes. The correlation between theoretical and the experimental data of (IR and UV-visible) spectra of the complexes are good. The metal complexes exhibited remarkable antimicrobial activity.