Vanadyl Sulfate - Synthesis, Structure, and Reactions

Synthesis, Structure, and Reactions

Vanadyl sulfate is most commonly obtained by reduction of vanadium pentoxide with sulfur dioxide:

V₂O₅ + 7 H₂O + SO₂ + H₂SO₄ → 2 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. 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:

SO₄ + C₅H₈O₂ + Na₂CO₃ → + Na₂SO₄ + 4 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.