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, L-4 = 2 tmeda (tmeda = Me2NCH2CH2Me2); X = 1, L = tetrahydrofuran (THF)) and [VX3(THF)(3)] (X = Br, I) to form the complexes [VX2(N2S2)] (1) and [VX2(N2S2)]X (2), respectively, [V-2(mu-Cl)(3)(THF)(6)]1 and N2S2 yield the V-IV complex [VOCl(N2S2]I (3). The pentadentate, dianionic ligand 2,6-bis(2'-mercaptophenylthio)dimethylpyridine, NS2S'(2-)(2), 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-morcaptoaniline 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.