Nickel(II), copper(II), and cobalt(II) complexes derived from a new unsymmetrical ONS donor Schiff base ligand: synthesis, characterization, crystal structure, and catalytic activities

A series of Ni(II), Cu(II), and Co(II) complexes, ML2, of a new thioether containing ONS donors have been synthesized, where L = deprotonated Schiff base. The analytical, spectral (FTIR, H-1 NMR, UV-vis), conductivity, and magnetic studies showed that the metal complexes possess octahedral geometry and are non-electrolytes. The structures of ligand as well as nickel(II) complex, NiL2, 2, were determined by single-crystal X-ray diffraction studies. The copper complex shows very good catalytic activities towards oxidation of organic thioethers to the corresponding sulfoxide predominantly using H2O2 as the oxidant. Ni(II), Cu(II), and Co(II) complexes, ML2, with a new thioether containing ONS donors were synthesized, where L = deprotonated Schiff base. The analytical, spectral (FTIR, 1H NMR, and UV-vis), conductivity, and magnetic studies show that the metal complexes possess octahedral geometry and are non-electrolytes. The coordination mode of ligand, 1, and nickel(II) complex, NiL2, 2, was determined by single-crystal X-ray diffraction studies. Here, the nickel is coordinated to two oxygens, two nitrogens, and two sulfurs of two tridentate ligands with slightly distorted octahedral environment around nickel. The copper complex shows very good catalytic activities towards oxidation of organic thioethers to the corresponding sulfoxide predominantly using H2O2 as the oxidant.