Copper(II) and nickel(II) complexes with two new bis(thiosemicarbazone) ligands: Synthesis, characterization, X-ray crystal structures and their electrochemistry behavior

• Ni(II) and Cu(II) complexes of new bis(thiosemicarbazone) ligands were prepared.
• Ligands act as N2S2 donor set and OH group has no effect on coordination geometry.
• New ligands can stabilize low oxidation state (+1) of nickel and copper.
• OH group has effect on redox potentials and reversibility of MII/MI couples.

Two new bis(thiosemicarbazone) ligands 2-[1-(2-{3-[2-({2-[(4-chloroanilino)carbothioyl]hydrazono}methyl)phenoxy]propoxy}phenyl)methylidene]-N1-(4-chlorophenyl)-1-hydrazinecarbothiamide (H2L1) and 2-[1-(2-{3-[2-({2-[(4-chloroanilino)carbothioyl]hydrazono}methyl)phenoxy]-2-hydroxypropoxy}phenyl)methylidene]-N1-(4-chlorophenyl)-1-hydrazinecarbothiamide (H3L2) were synthesized and characterized by FT-IR spectroscopy, 1H NMR spectroscopy and elemental analysis. Their nickel(II) and copper(II) complexes were prepared and characterized by UV–Vis spectroscopy, FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. Both ligands lose hydrazinic hydrogen atoms upon coordination and act as dianionic tetradentate donors. In [NiL1]·EtOH and [CuL1]·MeOH complexes metal centers are coordinated by two imine nitrogen atoms and two sulfur atoms with a distorted square planar coordination geometry. The geometrical distortion from square planar in the copper complex is greater than in the nickel complex. Cyclic voltammetry studies of Cu(II) and Ni(II) complexes in DMF show that all complexes able to stabilize low oxidation states of Cu(I) and Ni(I).

Two new bis(thiosemicarbazone) Schiff base ligands and their metal complexes with Cu(II) and Ni(II) were prepared and characterized by NMR, FT-IR, UV–Vis absorption spectroscopy, single crystal X-ray diffraction, CHN elemental analysis and cyclic voltammetry.Figure optionsDownload as PowerPoint slide