Versatile chelating behavior of aliphatic thiosemicarbazones in zinc and cobalt complexes

In this paper we report the synthesis of three new complexes of Zn(II) and Co(III) with two ligands, methyl pyruvate thiosemicarbazone (Hmpt) and alph a-ketoglutaric acid thiosemicarbazone (H(3)ct). The three compounds [Zn(H(2 )pt)(Hpt)Cl] (A), [Zn(H(2)ct)(2)]. H2O (B), [Co(H(2)ct)(Hct)]. H2O (C), are characterized by IR spectroscopic techniques and the structures determined by single-crystal X-ray diffraction analysis. In A an interesting feature is the different behavior of the two ligand molecules, one terdentate and t he other monodentate. The coordination geometry about zinc is better descri bed as intermediate between an ideal square pyramid and trigonal bipyramid, while in B and C the metals are six-coordinated in a distorted octahedral geometry. All compounds are monomeric. (C) 2000 Elsevier Science Ltd. All r ights reserved.