Vanadium, thiolate complexes

Hsu, H.F., W.C. Chu, C.H. Hung, and J.H. Liao. 2003. The first example of a seven-coordinate vanadium(III) thiolate complex containing the hydrazine molecule, an intermediate of nitrogen fixation. Inorg. Chem. 42 7369-7371. 

Vanadium(V) complexes of ligands with mixed thiolate-hydroxylate functionalities have been structurally characterized both in solution and in the solid state (90).457 Oxidation of this complex resulted in a vanadium(V) 72, 72—disulfenate complex with an unprecedented coordination mode (91).457 Complexes with 2-thio-3-benzoylhydantoin have also been reported.458 In addition, a recent solution study of vanadate with dithiothreitol (DTT) showed that the study of these complexes is quite tractable even in aqueous solution.459 The first hydrazide vanadium complex with S-donor ligands was structurally characterized (92).460... 

In addition to complexes with ON donor sets, complexes with bidentate N-donor atoms and other donors have been described. For example, after several solution studies the crystal structure of the bis(L-cysteine methyl ester)oxovanadium(IV) complex showed that the vanadium is coordinated by the amido nitrogens and thiolate sulfurs (128).561 The complexes and reactivity of a series of pyridine-2-thiolate complexes of V(IV, III, and II) have been characterized (129-131).651 The mass spectrometric fragmentation patterns of two of these complexes were investigated and show the formation of six 1 1 complexes and one 1 2 complex in the gas phase.651... 

Closely related are vanadium-copper complexes [VCu4(p -S>4(S2CN C4HgO)4 (SPh) ] n = 1-3) (Fig. 236), in which copper centers are linked by sulfido bridges to vanadium, and each copper carries either a dithiocarbamate or thiolate ligand (700,1747,1748). Vanadium-51 NMR studies suggest that in solution the different complexes are in equilibrium with one another. 

Cysteine is a fairly effective reducing agent for vanadate, but even so, under neutral conditions, the V(V) lifetime is sufficiently long that vanadium NMR spectra can be obtained. Four products (-243, -309, -393, and -405 ppm) have been reported. Of these complexes, the -243 and -309 ppm NMR signals apparently correspond to products containing two thiolate groups in the coordination sphere, whereas the -393 and -409 ppm products have one thiolate ligand [43],... 

A vanadium(II) tmeda complex with 2,6-dichlorothiophenolate has been reported with both S- and Cl-donor atoms (217).874 The thiolate donor atoms are trans to each other while the Cl atoms are trans to the N atoms in the tmeda ligand.874 The complex will react with azobenzene to give the phenylimido complex where one of the chloro-donor ligands is now trans to the imido nitrogen (218) 874 this complex is structurally similar to other imidovanadium(IV) complexes.643-646 A V11 cysteine methyl ester complex has been shown to reduce water to H2 but the mechanism of this process is not known.875... 

Some thiolate metal complexes, unlike the oxygen complexes referred to above are powerful antioxidants (see Chapter 1) and undergo inversion to prooxidant metal ions in sunlight. The iron, manganese, cobalt, vanadium and cerium dithiocarbamates (II) are typical examples of such restrained prooxidants. 

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