Electrochemical synthesis:: a convenient method for the preparation of neutral metal complexes with a thiosemicarbazone ligand

The interaction of the transition and post-transition metals manganese, iron, cobalt, nickel, zinc, cadmium and lead, with the ligand 4-N-methylthiosemicarbazone-2-pyridinecarboxaldehyde (HL) through an electrochemical procedure has been investigated. The novel complexes obtained via this synthetic route have the general formulae [M(L)(2)](H2O)(n) (n = 1-3.5). The crystal and molecular structures have been determined for the mononuclear complexes [MnL2]center dot H2O (2), [CoL2] (5), [NiL2]center dot H2O (7) and [PbL2] (11). Complexes 2, 5 and 7 exhibit a distorted octahedral polyhedron around the metal atom, whilst the lead derivative shows a particular coordination polyhedron that may be regarded as a distorted bipyramidal pentagonal structure, with one apical position filled by the metal lone pair. All these complexes have been fully characterized by elemental analysis, infrared spectroscopy, mass spectrometry, magnetic and conductivity measurements, and H-1, Cd-113 and Pb-207 NMR techniques.