Vanado-iodates

When vanadium pentoxide is dissolved in hot solutions of iodic acid, HIO₃, orange-yellow crystals of a sparingly soluble substance having the composition V₂O₅.I₂O₅.4H₂O are obtained. The four molecules of water are a factor in the constitution of the acid, since they cannot be removed without decomposition taking place. Several other similarly constituted compounds have been prepared, viz. V₂O₅.2I₂O₅.10H₂O; V₂O₅.I₂O₅.5H₂O; 2V₂O₅.3I₂O₅.18H₂O. These all undergo hydrolysis with precipitation of vanadium pentoxide on being boiled with water. By the action of ammonium hydrogen iodate, NH₄H(IO₃)₂, and potassium hydrogen iodate, KH(IO₃)₂, on the acid V₂O₅I₂O₅.4H₂O, salts have been prepared which have the following compositions: (NH₄)₂O.V₂O₅.2I₂O₅ and K₂O.V₂O₅.2I₂O₅. The vanado-iodic acids are probably derivatives of "ortho-iodic acid," I(OH)₅. The compound V₂O₅I₂O₅.4H₂O, therefore, has the following probable constitution: