Metal complexes of new thiocarbohydrazones of Cu(I), Co(II), and Ni(II); identification by NMR, IR, mass, UV spectra, and DFT calculations

Substituted thiocarbohydrazones were synthesized to study their complexation capability towards Cu(I), Co(II), and Ni(II) salts. The Cu(I) complexes showed ligation of one mole of Cu(I)Br to one of the synthesized ligands to form a cationic–anionic metal complex. Co(II) and Ni(II) complexes were determined due to the chelating of equal equivalents of both ligands and metal salts to form monodentate metal dihalogenated complexes. Metal complexes were characterized by mass spectrometry, IR, NMR, UV spectra, and elemental analyses. Theoretical calculations were performed using density functional theory (DFT) at the B3LYP level with 6–31 + G(d) and LANL2DZ basis sets to access reliable results to the experimental values. The calculations were performed to obtain the optimized molecular geometry, charge density distribution, extent of distortion from regular geometry, the HOMO (highest occupied molecular orbital), the LUMO (lowest unoccupied molecular orbital), the molecular electrostatic potential (MEP), reactivity index (ΔE), dipole moment (D), global hardness (η), softness (σ), electrophilicity index (ω), and chemical potential. The calculations confirmed that the investigated complexes have a reliable geometry, agreeing with the experimental observation.