Platinum Dicyanide, Platinous Cyanide, Pt(CN)2, appears to have been first obtained by Doebereiner as the result of heating mercuric platinocyanide, HgPt(CN)4. It also results on treating the double potassium salt, K2Pt(CN)4 with chlorine, and by heating the ammonium salt, (NH4)2Pt(CN)4, to 200° C. or 300° C. When mercuric cyanide is added to a solution of an alkali chlor-platinite, the liquid is decolorised, and platinous cyanide is deposited as a pale yellow precipitate.4 Prepared in these ways, platinous cyanide possesses a yellow colour. It is insoluble in alkalies and potassium cyanide, for which reason it cannot be used in preparing platinocyanides. When heated it burns, yielding metallic platinum.
A soluble form of platinous cyanide is obtained as a yellow precipitate by decomposing a solution of a platinocyanide with sulphuric acid. It dissolves easily in alkalies and in potassium cyanide solution, but is usually contaminated with small quantities of sulphate. |