Vanadyl sulfate

Vanadyl sulfate
IUPAC name Oxovanadium(2+) sulfate
Other names Basic vanadium(IV) sulfate Vanadium(IV) oxide sulfate Vanadium(IV) oxysulfate
Identifiers
CAS number	27774-13-6 Y
Properties
Molecular formula	VOSO4
Molar mass	163.00 g/mol
Appearance	Blue crystalline solid
Melting point	105 °C decomp.
Solubility in water	Soluble
Hazards
EU Index	Not listed
Main hazards	Irritant
Flash point	Non-flammble
Related compounds
Other anions	Vanadyl chloride Vanadyl nitrate
Other cations	Vanadium(III) sulfate
Related compounds	Vanadyl acetylacetonate
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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."^[1] Vanadyl sulfate is an intermediate in the extraction of vanadium from petroleum residues, a major commercial source of vanadium.^[2] 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.

Synthesis, structure, and reactions

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:^[3]

[V(O)(H₂O)₄]SO₄ + C₅H₈O₂ + Na₂CO₃ → [V(O)(C₅H₇O₂)₂ + 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.

Occurrence in nature

Like most water-soluble sulfates, vanadyl sulfate is only rarely found in nature. Anhydrous form is pauflerite, a mineral of fumarolic origin. Hydrated forms, also rare, include hexahydrate (stanleyite), pentahydrates (minasragrite, orthominasragrite, and anorthominasragrite) and trihydrate - bobjonesite.^{[citation needed]}

References

1. ^ ^{a b} Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 1157. ISBN 0-08-022057-6. 
2. ^ Günter Bauer, Volker Güther, Hans Hess, Andreas Otto, Oskar Roidl, Heinz Roller, Siegfried Sattelberger in "Vanadium and Vanadium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
3. ^ Bryant, Burl E.; Fernelius, W. Conard (1957), "Vanadium(IV) Oxy(acetylacetonate)", Inorg. Synth. 5: 113–16, doi:10.1002/9780470132364.ch30