Structural studies of a copper(II) complex with inequivalent 2-acetylpyridine 3-piperidylthiosemicarbazonato ligands and a nickel(II) complex with different modes of coordination by the two thiosemicarbazonato moieties of 1-phenylglyoxal bis{N(4)-diethylthiosemicarbazone}

The crystal structure of a copper(II) complex of 2-acetylpyridine 3-piperid ylthiosemicarbazone, [Cu(Acpip)(2)], indicates a tridentate, monoanionic li gand (i.e., pyridine nitrogen, imine nitrogen and thiolato sulfur atoms) an d a bidentate, monanionic ligand (i.e., imine nitrogen and thiolato sulfur atoms). The stereochemistry approaches square pyramidal with the bidentate Ligand occupying an apical (imine nitrogen atom) and basal (thiolato sulfur atom) position. The structure of a nickel(II) complex of 1-phenyl-glyoxal N(4)-diethylthiosemicarbazone, [Ni(P4DE)], has a 4-6-5 trichelate system ra ther than the 5-5-5 system common to bis(thiosemicarbazones). Coordination of the hydrazinic nitrogen atom of the "phenyl arm" along with the thiolato sulfur atom provides the 4-membered chelate ring.