Platinum Subsilicide, Pt₂Si

Diplatinum Silicide, Platinum Subsilicide, Pt₂Si, was apparently first obtained by Colson by prolonged heating of platinum surrounded by lampblack in a Hessian crucible. Lebeau prepared it by heating the monosilicide with tin and washing the product with potassium hydroxide, the subsilicide constituting the residue. Vigouroux prepared the subsilicide by heating the metal with 10 to 100 times its weight of silicon in an electric furnace to such a high temperature that excess of the silicon volatilised.

The product is a crystalline substance, hard and brittle, capable of being pounded to powder in a mortar. Density 13.8 at 18° C. Heated in chlorine, silicon chloride is formed, leaving a residue of platinum.