Fluoroxyperniobates

Niobium Peroxyfluorides or Fluoroxyperniobates. - Like niobic acid, the alkali niobium oxyfluorides have the property of taking up active oxygen by reaction with hydrogen peroxide.

Potassium Niobium Peroxyfluoride

When potassium niobium oxyfluoride, K₂NbOF₅.H₂O, is dissolved in 3 per cent, hydrogen peroxide, fine, white, greasy leaflets of potassium niobium peroxyfluoride or potassium fluoroxy perniobate, K₂NbO₂F₅.H₂O or 2KF.NbO₂F₃.H₂O, are obtained. This compound is stable in dry air. At 100° C. it loses water and at 150° C. it loses oxygen. Its aqueous solutions decompose only very slowly; the solubility is decreased by the addition of hydrogen peroxide and increased by the addition of hydrofluoric acid.

Sodium Niobium Peroxyfluoride

Sodium Niobium Peroxyfluoride or sodium fluoroxy perniobate, Na₃NbO₂F₆.H₂O or 3NaF.NbO₂F₃.H₂O, is prepared by the action of hydrogen peroxide on sodium niobium oxyfluoride, 3NaF.NbOF₃. It forms yellow, almost transparent crystals, which become cloudy on exposure to the air.

Rubidium Niobium Peroxyfluoride

Rubidium Niobium Peroxyfluoride or rubidium fluoroxyperniobate, Rb₂NbO₂F₅.H₂O or 2RbF.NbO₂F3.H₂O, is obtained similarly, as thin, yellow plates, from rubidium niobium oxyfluoride, 2RbF.NbOF₃.