Chromium(VI) oxide peroxide Names IUPAC name Other names Identifiers ChEBI ChemSpider 101104 Properties CrO(O2)2 Molar mass 131.991 g·mol−1 Appearance Dark blue soluble (decomposes) Hazards Occupational safety and health (OHS/OSH): May suddenly explode if unstabilized/dry, toxic and create highly carcinogenic chromium fumes.
Chromium(VI) oxide peroxide is a chemical compound with the chemical formula CrO(O2)2. The name “chromium(VI) oxide peroxide” is also given to a collection of chromium coordination complexes. They have the formula CrO(O2)2L where L is a ligand. These species are dark blue and often labile. They all feature one oxo ligand and two peroxo ligands, with the remaining coordination sites occupied by water, hydroxide, diethyl ether, pyridine, or other Lewis bases.[1]
Chromium(VI) oxide peroxide is formed by the addition of acidified hydrogen peroxide solutions to solutions of metal chromates or dichromates, such as sodium chromate or potassium dichromate. The generally yellow chromates or orange dichromates turn to dark blue as “chromium(VI) oxide peroxide” forms:
CrO2−4 + 2 H2O2 + H+ → [CrO(O2)2OH]− + 3 H2O
The structure of the pyridine complex has been determined crystallographically.[2] Adducts with other N-heterocycles have also been characterized similarly.[3]
Aqueous chromium(VI) oxide peroxide decomposes in a few seconds, turning green as chromium(III) compounds are formed.[4]
2 CrO(O2)2 + 7 H2O2 + 6 H+ → 2 Cr3+ + 10 H2O + 7 O2
Stable adducts of the type CrO(O2)2L include those with L = diethyl ether, 1-butanol, ethyl acetate, or amyl acetate. They form by adding a layer of the organic solvent above the chromate/dichromate solution and shaking during the addition of hydrogen peroxide.
The etherate, bis(pyridine) and pyridine complexes of this compound have been found to be effective oxidants in organic chemistry.[5]
CrO(O2)2 is sometimes said to have a “butterfly-like” structure due to its arrangement according to valence bond theory.
- Tetraperoxochromate – an similarly synthesized analogous chromium(V) peroxide complex
- Experimental details and photo (in German)
- Losing fingers to chemistry on YouTube (8 November 2012). Professor Martyn Poliakoff of the University of Nottingham demonstrates the synthesis on Periodic Videos.
