Carbonyl cuprous sulphate, (CuCO)₂SO₄

On decolorizing an aqueous solution of cupric sulphate with carbon monoxide, and evaporating in an atmosphere of this gas, a solid complex salt was obtained by Joannis. He ascribed to it the formula (CuCO)₂SO₄,H₂O. The great instability of the product is indicated by its decomposition by water into copper and cupric sulphate. In its constitution this compound resembles the carbonyl derivatives of the copper halides, the proportion of carbon monoxide to copper in its molecule being in the ratio of one molecule to one atom.