Vanadium(II) sulfate

Vanadium(II) sulfate describes a family of inorganic compounds with the formula VSO₄(H₂O)_x where 0 ≤ x ≤ 7. The hexahydrate is most commonly encountered. It is a violet solid that dissolves in water to give air-sensitive solutions of the aquo complex. The salt is isomorphous with [Mg(H₂O)₆]SO₄. Compared to the V–O bond length of 191 pm in [V(H₂O)₆]³⁺, the V–O distance is 212 pm in the [V(H₂O)₆]SO₄. This nearly 10% elongation reflects the effect of the lower charge, hence weakened electrostatic attraction.^[1]

Vanadium(II) sulfate

Identifiers
CAS Number	anhydrous: 13566-06-8 Y hexahydrate: 12439-96-2
3D model (JSmol)	anhydrous: Interactive image hexahydrate: Interactive image heptahydrate: Interactive image
ChemSpider	anhydrous: 145979 hexahydrate: 77429427
ECHA InfoCard	100.233.281
EC Number	anhydrous: 806-241-5
PubChem CID	anhydrous: 166848 heptahydrate: 22613976
UNII	anhydrous: IO5B4EXJYI Y
CompTox Dashboard (EPA)	anhydrous: DTXSID60929102
InChI anhydrous: InChI=1S/H2O4S.V/c1-5(2,3)4;/h(H2,1,2,3,4);/q;+2/p-2 Key: VLOPEOIIELCUML-UHFFFAOYSA-L hexahydrate: InChI=1S/H2O4S.6H2O.V/c1-5(2,3)4;;;;;;;/h(H2,1,2,3,4);6*1H2;/q;;;;;;;+2/p-2 Key: LRLWNWIKXRXQMV-UHFFFAOYSA-L
SMILES anhydrous: [V+2].[O-]S([O-])(=O)=O hexahydrate: O.O.O.O.O.O.O=S(=O)([O-])[O-].[V+2] heptahydrate: O.O.O.O.O.O.O.O=S(=O)([O-])[O-].[V+2]
Properties
Chemical formula	H12O10SV
Molar mass	255.09 g·mol−1
Appearance	violet solid
Density	1.910 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The heptahydrate has also been crystallized. The compound is prepared by electrolytic reduction of vanadyl sulfate in sulfuric acid.^[1][2] The crystals also feature [V(H₂O)₆]²⁺ centers but with an extra water of crystallization. The salt is isomorphous with ferrous sulfate heptahydrate.^[3] A related salt is vanadous ammonium sulfate, (NH₄)₂V(SO₄)₂·6H₂O, a Tutton's salt isomorphous with ferrous ammonium sulfate.^[4]