Thiofunctional Vanadium Complexes

The neutral tetradentate ligand 1,6-bis(2‘-pyridyl)-2,5-dithiahexane (N2S2), containing two thioether functions, reacts with [VX2L4] (X = Br, L4 = 2 tmeda (tmeda = Me2NCH2CH2NMe2); X = I, L = tetrahydrofuran (THF)) and [VX3(THF)3] (X = Br, I) to form the complexes [VX2(N2S2)] (1) and [VX2(N2S2)]X (2), respectively. [V2(μ-Cl)3(THF)6]I and N2S2 yield the VIV complex [VOCl(N2S2]I (3). The pentadentate, dianionic ligand 2,6-bis(2‘-mercaptophenylthio)dimethylpyridine, NS2S‘22-, which contains two thioether (S) and two thiophenolate (S‘) functions, reacts with [VBr3(THF)3] to afford [VBr(NS2S‘2)] (4). The complex [VO(Cl)S‘NS‘] (5; H2S‘NS‘ is the Schiff base formed between o-mercaptoaniline and o-mercaptobenzaldehyde) is obtained by redox interaction between [VCl3(THF)3] and 2,2‘-dithiodibenzaldehyde in the presence of o-mercaptoaniline.The crystal and molecular structures have been obtained for 3·THF, 4·THF, and 5·n-C5H12. The relevance of these compounds and their formation for the interaction between vanadium and thiofunctional biomolecules is addressed.