Palladous Selenide, PdSe

Berzelius found that palladium and selenium unite to form a refractory, grey Palladous Selenide, PdSe when heated together, their union being accompanied with evolution of heat.

Roessler obtained the selenide by igniting palladosammine chloride, PdCl₂.2NH₃, with half its weight of selenium, using borax as a flux. The product has a metallic appearance, with a fine-grained fracture. It melts at a lower temperature than silver (960° C.) without loss of selenium even in air. It dissolves completely in aqua regia, and serves to illustrate the observation that selenides are usually more readily attacked by acids than the corresponding sulphides.