Structural, Spectral (IR and UV/Visible) and Thermodynamic Properties of Some 3d Transition Metal(II) Chloride Complexes of Glyoxime and Its Derivatives: A DFT and TD-DFT Study

Abstract

Metal complexes bearing vic-dioxime ligands have been extensively used as analytical and biochemical reagents, and are well-known antimicrobial agents. Herein is reported a DFT study on the molecular structures, thermodynamic properties, chemical reactivity and spectral properties of some 3d metal(II) chloride complexes of glyoxime. The functionals B3LYP and CAM-B3LYP have each been used in conjunction with LANL2DZ for the metal(II) ions (Fe²⁺, Co²⁺, Ni²⁺ and Cu²⁺) and the Poplestyle basis set 6-31G+(d,p) for the rest of the elements, to perform theoretical calculations. The metal complexation abilities of the glyoxime ligands studied in this work have been evaluated on the basis of metal-ligand binding energies. These ligands were found to have high affinities towards Ni(II) and Fe(II) ions, and all complexation reactions were found to be thermodynamically feasible. Ligand-to-metal electron donations in the complexes studied have been revealed by natural population analysis. The fully optimized geometries of the complexes have adopted square planar structures around the central metal ions. On the basis of orbital composition analysis, the UV-Vis electronic absorption bands of these molecules have been attributed mainly to MLCT, LMCT and d-d electronic transitions involving metal-based orbitals.