
Vanadium(III) sulfate

Vanadium(III) sulfate is the inorganic compound with the formula V2(SO4)3. It is a pale yellow solid that is stable to air, in contrast to most vanadium(III) compounds. It slowly dissolves in water to give the green aquo complex [V(H2O)6]3+.
The compound is prepared by treating V2O5 in sulfuric acid with elemental sulfur: 
This transformation is a rare example of a reduction by elemental sulfur. 
When heated in vacuum at or slightly below 410 °C, it decomposes into vanadyl sulfate (VOSO4) and SO2. Vanadium(III) sulfate is stable in dry air but upon exposure to moist air for several weeks forms a green hydrate form. 
Vanadium(III) sulfate is a reducing agent.