Potassium hexacyanochromate(III)

Potassium hexacyanochromate(III) is a coordination compound with the formula K₃[Cr(CN)₆]. It consists of three potassium cations and a central hexacyanometallate with [Cr(CN)₆]³⁻ anion. It is a yellow, air-stable, paramagnetic solid. It is not stable at higher temperatures, forming chromium(III) hydroxide precipitate.

The salt is prepared by treating chromium trioxide, dissolved in concentrated hydrochloric acid, with ethanol in a redox reaction. Following the solution is evaporated to dryness. The residue is dissolved in a boiling solution of KCN. The evaporation is repeated, but not till dryness. The concentrated solution is left in the cold to sulphur.

The Cr(II) derivative is unusual and has been little studied.