Synthesis,characterization, crystal structure and electrochemical behavior of a nickel(II) complex of 5,6-dihydro-2H-pyran-3-aldehyde thiosemicarbazone

A new Ni^II complex of 5,6-dihydro-2H-pyran-3-aldehyde thiosemicarbazone (HDPTSC) has been synthesized and characterized by microanalyses, magnetic susceptibility, molar conductance measurements and by spectral methods (i.r., u.v.–vis., ¹H-n.m.r.). The structure of [Ni(DPTSC)₂] · B DMF has been solved using X-ray diffraction and found to be highly symmetrical with a trans -arrangement of the two bidentate ligands. The thiosemicarbazone coordinates as an anionic ligand via the thiosemicarbazone moietys azomethine nitrogen and thiolate sulfur [on loss of the N2 hydrogen]. The electrochemical behavior of the ligand and its Ni^II complex, determined by cyclic voltammetry, shows that the redox process of the ligand was highly irreversible, whereas the redox process of the Ni^II complex was observed as a one electron transfer process in a quasi-reversible and diffusion-controlled reaction.