Structural and spectral studies of 2-pyridineformamide thiosemicarbazone and its complexes prepared with zinc halides

Reduction of 2-cyanopyridine by sodium in dry methanol in presence of thios emicarbazide produces 2-pyridineformamide thiosemicarbazone, HAm4DH. The cr ystal structure of HAm4DH, which has a number of intermolecular interaction s involving its five NH hydrogen atoms, has been solved. Crystal structures of the complexes prepared by reaction of HAm4DH with zinc(II) chloride, br omide and iodide have also been obtained. Neutral HAm4DH is coordinated via the pyridyl nitrogen, imine nitrogen and thione sulfur atoms, and each com plex is five-coordinate with two halogen ligands. The structures of the thr ee complexes are best described as square pyramidal with [Zn(HAm4DH)I-2] ha ving the largest distortion toward a trigonal bipyramid.