Carbonyl Platinum Monosulphide, PtS.CO

Carbonyl Platinum Monosulphide, PtS.CO, is thrown down as a brown precipitate when hydrogen sulphide is passed into a solution of carbonyl platinum dichloride in hydrochloric acid:

PtCl₂.CO + H₂S = PtS.CO + 2HCl.

It is an unstable substance, decomposing in vacuo, and burning with a slight explosion when heated to 800° or 400° C., yielding platinum, sulphur, and oxides of carbon and sulphur.