They all feature oxo ligand and two peroxo ligands, with the remaining coordination sites occupied by water, hydroxide, ether, 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: The structure of the pyridine complex has been determined crystallographically.

They form by adding a layer of the organic solvent above the chromate/dichromate solution and shaking during the addition of hydrogen peroxide.

[5] CrO5 is sometimes said to have a "butterfly-like" structure due to its arrangement according to valence bond theory.