Synthesis, Characterization and Molecular Structure of 2-Pyridyl-formamide N(4)-Dimethylthiosemicarbazone and Some Five-Coordinated Zinc(II) and Cadmium(II) Complexes

Abstract

Abstract Sodium in dry methanol reduces 2-cyanopyridine in the presence of N(4)-dimethylthiosemicarbazide to produce 2-pyridyl-formamide N(4)-dimethylthiosemicarbazone, HAm4DM. Com­plexes with zinc(II) and cadmium(II) of formulae [M(Am4DM)(OAc)]2 and [M(HAm4DM)X2] (M = Zn or Cd, X = Cl, Br or I) have been prepared and characterized by spectro­scopic techniques. In addition, the crystal structures of HAm4DM, [Zn(HAm4DM)Br2], and [Cd(HAm4DM)l2] DMSO have been solved. HAm4DM is in the zwitterionic form with a hydrogen bonding interaction between the iminium hydrogen and the thiolato sulfur atom. Co­ ordination of the neutral thiosemicarbazone ligand is via the pyridyl nitrogen, imine nitrogen and thione sulfur atoms, while the anionic ligand in [M(Am4DM)(OAc)]2 coordinates with the same two nitrogen atoms and a thiolato sulfur atom. The [M(HAm4DM)X2] complexes are 5-coordinate with the tridentate thiosemicarbazone and two halogen ligands approaching a square pyramidal stereochemistry.