Biological activity of complexes derived from thiophene-2-carbaldehyde thiosemicarbazone. Crystal structure of [Ni(C6H6N3S2)(2)]

The crystal structure of [Ni(L-III)(2)] (1), where HLIII = thiophene-2-carb aldehyde thiosemicarbazone, consists of monomeric entities where the nickel (II) ions exhibit distorted square planar geometry. The two bidentate thios emicarbazone ligands are centrosymmetric. (CS)-S-... van der Waals' links a nd nonbonded intramolecular interactions are present in the structure. The biological activity of 1 is compared to that of the free ligand, and the co balt (III) (2) and copper(H) (3) derivatives. The observed order of cytotox icity against melanoma B16F10 and Friend erythroleukemia. cells is: 1 less than or equal to ligand <2 <3. A structure-activity correlation using Exten ded-Huckel MO calculations is described. (C) 2001 Elsevier Science BY All r ights reserved.