Monocarbonyl Platinum Di-iodide, PtI₂.CO

Monocarbonyl Platinum Di-iodide, PtI₂.CO, is obtained by adding dilute hydriodic acid to a solution of the carbonyl platinum dichloride in hydrochloric acid:

PtCl₂CO + 2HI = PtI₂.CO + 2HCl.

A brick-red, amorphous precipitate is obtained. This is purified by solution in and recovery from hydriodic acid and subsequent recrystallisation from benzene.

It may also be obtained by evaporating the mixed carbonyl derivatives, obtained by Schutzenberger's method, with concentrated hydriodic acid, and recrystallising from benzene.

It yields red crystals, exhibiting a violet shimmer. They melt at 140° to 150° C., and decompose as the temperature is still further raised. They are decomposed by water rather slowly, whilst alkalies liberate metallic platinum.

With potassium iodide a double salt, PtI₂.CO.KI, is obtained as yellowish brown scales, which melt at 150° to 180° C. with decomposition. Other salts have been prepared, both with inorganic and with organic iodides.