Potassium Chloriridate, K₂IrCl₆

Potassium Chloriridate, K₂IrCl₆, is prepared by heating a mixture of iridium and potassium chloride in chlorine, and purifying the product by crystallisation from its aqueous solution. The mother- liquor contains some chloriridite, which, however, may be converted into the iridate by addition of chlorine water. The salt may also be obtained by decomposing sodium chloriridate with potassium chloride or by boiling a solution of the ammonium salt with potassium hydroxide. It crystallises in black, regular octahedra, which are but slightly soluble in water, and insoluble in saturated potassium chloride solution, as also in alcohol. The aqueous solution on boiling is partially decomposed, yielding the chloriridite. When heated strongly, metallic iridium and potassium chloride remain. Heated to 440° C. in a current of hydrogen chloride, the anhydrous, insoluble trichloride is obtained, together with soluble chloriridite.

Potassium chloriridate is isomorphous with potassium chlorplatinate, K₂PtCl₆.