Activity of Some Vanadium Peroxo Complexes

Catalytic Activity of Some Vanadium Peroxo Complexes 

A question that must be answered is why nature has chosen vanadium as a prosthetic group in bromoperoxidases. As pointed out by Djor jevic (75), the electron-rich peroxide group will easily form complexes with metal ions of low configuration, such as molybdenum and 

Selective epoxidation of olefins by vanadium(V) alkyl peroxo complexes has also been reported (76). These complexes are very effective stereo-selective reagents for the transformation of olefins into epoxides. The mechanism consists of binding of the olefin to the metal to displace one of the peroxo-oxygen atoms, nucleophilic attack of the bound oxygen atom on the coordinated electron-deficient olefin, dissociation of the epoxide, and reaction of the remaining vanadium intermediate with 

From comparison of antitumor activity and toxicity of hetero-ligand vanadium(V) complexes, Djordjevic and Wampler (79) arrived at the conclusion that the hetero-ligand is able to affect the redox potential of the V(V)/V(IV) couple in such a way that intramolecular electron transfer can occur within the V(V)-peroxoadduct. As a consequence, vanadium(V) is reduced to the IV state, and the peroxo group is oxidized to a superoxide radical. It is conceivable that such a species is present also during the reaction of vanadium bromoperoxidase with H2O2. However, there is no evidence for a radical type of reaction with bro-moperoxidases. 

It would be of considerable interest to see whether vanadium-peroxo complexes are also able to oxidize bromide and display kinetic behavior similar to that of the vanadium-containing bromoperoxidases. In this respect the complexes reported by Li et al. (80) may provide a useful contribution. Conversely, some attention should be paid to whether bromoperoxidases show specificity only toward bromide or iodide. These enzymes may perhaps be tuned to catalyze the oxidation and oxygenation of other nucleophiles. 

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Catalytic Activity of Some Vanadium Peroxo Complexes Structural Properties of Vanadium Peroxo Complexes Vanadium in Mushrooms Vanadium in Coal... 

I. Catalytic Activity of Some Vanadium Peroxo Complexes... 

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