Structural Studies of 2,6-Diacetyl- and 2,6-Diformylpyridine Bis(thiosemicarbazones)

Although a large number of crystal structures of heterocyclic thiosemicarbazones have recently appeared in the literature, few structures of heterocyclic bis(thiosemicarbazones) or their metal complexes have been reported. Complexes of iron(II), indium(III), tin(IV), bismuth(III) involve bis(thiosemicarbazones) coordinating as N3S2 pentadentate ligands, often resulting in 7-coordinate complexes. In contrast, complexes with zinc(II) are often binuclear with thiosemicarbazone moieties of a bis(thiosemicarbazone) coordinating to two different zinc centers. Also included in this study is the structure of the first complex with a 2,6-diformylpyridine bis(thiosemicarbazone) ligand, a 4-coordinate nickel(II) complex with unusual coordination.