Navigation: Vanadyl Sulphate

Vanadyl Sulphate

Vanadyl(IV) sulfate, VOSO4, is a well known inorganic compound of vanadium. This very hygroscopic blue solid is one of the most common sources of vanadium in the laboratory, reflecting its high stability. It features the vanadyl ion, VO2+, which has been called the "most stable diatomic ion." Vanadyl sulfate is an intermediate in the extraction of vanadium from petroleum residues, a major commercial source of vanadium. Vanadyl sulfate is a component of some food supplements and drugs. Vanadyl compounds mimic the effects of insulin, although humans seem to have no dietary requirement for vanadium.

Vanadyl sulfate is most commonly obtained by reduction of vanadium pentoxide with sulfur dioxide:
V2O5 + 7 H2O + SO2 + H2SO4 ? 2 [V(O)(H2O)4]SO4
From aqueous solution, the salt crystallizes as the pentahydrate, the fifth water is not bound to the metal in the solid. Viewed as a coordination complex, the ion is octahedral, with oxo, four equatorial water ligands, and a monodentate sulfate.[1] The V=O bond distance is 160 pm in length, about 50 pm shorter than the V–OH2 bonds. In solution, the sulfate ion dissociates rapidly.

Being widely available, vanadyl sulfate is a common precursor to other vanadyl derivatives, such as vanadyl acetylacetonate:

[V(O)(H2O)4]SO4 + 2C5H8O2 + Na2CO3 -> [V(O)(C5H7O2)2] + Na2SO4 + 5 H2O + CO2

In acidic solution, oxidation of vanadyl sulfate gives yellow-coloured vanadyl(V) derivatives. Reduction, e.g. by zinc, gives vanadium(III) and vanadium(II) derivatives, which are characteristically green and violet, respectively.

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