Introducing a novel crystal form of pyruvic acid thiosemicarbazone and its sodium salt

The reaction of thiosemicarbazide and sodium pyruvate has been thoroughly studied and the novel crystal form of pyruvic acid thiosemicarbazone (H2pt) and its sodium salt were obtained. Compounds were characterized by IR spectra, melting points, elemental analysis and conductometric measurements, as well as single-crystal X-ray analysis. A detailed comparative analysis of crystal structures of these compounds is given, as well as comparison with some of the earlier known complexes containing H2pt. The two novel crystal structures exhibit notably different hydrogen bonding patterns, mutually and in comparison with previously reported crystal form of H2pt. All crystal structures are stabilized by extensive network of N-H...O, O-H...O and N-H...S hydrogen bonds. The cyclic hydrogen bonding motif involving the thioureido moieties of the ligand is the only one which repeats in each structure.