Gold(III) oxide
Gold oxide is the most stable oxide of gold. It is a red-brown, thermally unstable solid that decomposes at 160 °C. The hydrated form is weakly acidic and dissolves in concentrated alkali to form salts that are believed to contain the Au4− ion.
Anhydrous AuO can be prepared by heating amorphous hydrated gold oxide with perchloric acid and an alkali metal perchlorate in a sealed quartz tube at a temperature of around 250 °C and a pressure of around 30 MPa.
