Transition metal complexes with thiosemicarbazide-based ligands: Part 59. Synthesis, structures and electrochemical properties of cobalt(III) complexes with 2-acetylpyridine S-methylisothiosemicarbazone

The paper is concerned with the crystal structure and electrochemical characteristics of the cobalt(III) complexes with 2-acetylpyridine S-methylisothiosemicarbazone (HL), of the coordination formulas [CoL2]NO3·MeOH (1), [CoL2]Br·MeOH (2), [CoL2]HSO4·MeOH (3), [CoL2]2[CoII(NCS)4] (4), [Co(HL)(L)]I2·2 MeOH (5), and [Co(HL)(L)][CoIICl4]·MeOH (6), as well as of the structure of HL. In all the complexes, Co(III) is situated in a slightly deformed octahedral environment formed by six nitrogen atoms of the two HL molecules in the meridional positions. The ligands coordinate with Co(III) in a usual way, i.e. via the pyridine, azomethine, and isothioamide nitrogen atoms, each forming two five-membered metallocycles. Electrochemical studies of the ligand and the complexes in DMF show that the electrode processes are accompanied by chemical reactions and the corresponding mechanism was proposed. The obtained complexes were also characterized by elemental analysis, conductometric measurements and UV–Vis and IR spectroscopy.

Graphical abstractThe subject of the work is the synthesis and single crystal X-ray analysis of the cobalt(III) complexes with 2-acetylpyridine S-methylisothiosemicarbazone (HL), of the coordination formulas [CoL2]NO3·MeOH (1), [CoL2]Br·MeOH (2), [CoL2]HSO4·MeOH (3), [CoL2]2[CoII(NCS)4] (4), [Co(HL)(L)]I2·2 MeOH (5), and [Co(HL)(L)][CoIICl4]·MeOH (6), as well as of the structure of HL. In all the complexes, Co(III) is situated in a slightly deformed octahedral environment formed by six nitrogen atoms of the two HL molecules in the meridional positions.Figure optionsDownload full-size imageDownload as PowerPoint slide