Potassium tetraperoxochromate(V)
Potassium peroxochromate, potassium tetraperoxochromate(V), or simply potassium perchromate, is an inorganic compound having the chemical formulaK3[Cr(O2)4]. It is a red-brown paramagnetic solid. It is the potassium salt of tetraperoxochromate(V), one of the few examples of chromium in the +5 oxidation state and one of the rare examples of a complex stabilized only by peroxide ligands. This compound is used as a source of singlet oxygen.
Preparation
Potassium peroxochromate is prepared by treating potassium chromate with hydrogen peroxide at 0 °C:
- 2 CrO2−4 + 8 H2O2 → 2 [Cr(O2)4]2− + 8 H2O
The intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V):
- 2 [Cr(O2)4]2− + 2 OH− + H2O2 → 2 [Cr(O2)4]3− + 2 H2O + O2
Thus, the overall reaction is:
- 2 CrO2−4 + 9 H2O2 + 2 OH− → 2 [Cr(O2)4]3− + 10 H2O + O2
The compound decomposes spontaneously at higher temperatures.