Caesium Pentachlor-platinite, Cs₂PtCl₅

Caesium Pentachlor-platinite, Cs₂PtCl₅, is obtained when chlorine is passed into a cold solution of caesium tetrachlor-platinite, Cs₂PtCl₄; it also results when hydrated platinum sesquioxide is dissolved in hydrochloric acid containing caesium chloride. It is a green, crystalline, insoluble salt. When warmed with water it readily decomposes, yielding the tetrachlor-platinite. Exposure to sunlight likewise accelerates its decomposition.