Carbonyl Platinum Dibromide, PtBr₂.CO

Carbonyl Platinum Dibromide, PtBr₂.CO, was prepared by Pullinger by passing a slow stream of dry carbon monoxide over platinum dibromide gradually heated to about 180° C.

It is also prepared by evaporating a solution of monocarbonyl platinum dichloride in hydrochloric acid on the water-bath in a current of hydrogen bromide. Upon recrystallisation from benzene it yields orange-red crystals, entirely free from platinum and platinous bromide.

The crystalline needles melt at 177.7° C. They dissolve in water to a red solution, which, however, almost instantly blackens, the black deposit, however, being soluble in hydrobromic acid.

When melted in a current of carbon dioxide it yields platinum dibromide.

With bromides of the alkali metals, etc., it yields a series of crystalline double salts.