Orthopervanadates

The ammonium salt, (NH₄)₃VO₆.2½H₂O, is obtained by dissolving ammonium metavanadate in excess of concentrated ammonia solution, cooling to 0° C., adding 30 per cent, hydrogen peroxide, and then precipitating with alcohol. The product, after washing with ether and drying, is pale blue, and probably has the constitution



With large excess of hydrogen peroxide an indigo-blue salt which contains more oxygen, probably VO₂(OH)(O.ONH₄)₂, is obtained.

Potassium Orthopervanadate, K₃VO₆.2½H₂O, is also blue, and is prepared similarly to the ammonium salt.

Vanadium oxyfluorides also react with hydrogen peroxide to yield complex compounds. These are not so well defined as in the case of the peroxyfluorides of niobium and tantalum.