Indirect evidences of desulfurization of a thiosemicarbazonecopper(II) system in aqueous basic medium

Aqueous basic solutions of the CuII/HL/NO3- system (HL = C8H10N4S, pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) are acidified to pH 5 yielding the [{Cu(L)}2(NO3)](OH) · 5H2O (1) and [{Cu(L)(H2O)}{Cu(L)(SO4)}] · 5H2O (2) complexes. The crystal structures consist of dinuclear non-centrosymmetric entities containing CuII ions in square-pyramidal environments. The sulfato group in 2 arises from the desulfurization of thiosemicarbazone ligands.