Silver carbonyl ferrocyanide, Ag₃[Fe(CN)₅CO]

Silver carbonyl ferrocyanide, Ag₃[Fe(CN)₅CO], is obtained as a white curdy precipitate on addition of the potassium salt to silver nitrate solution in the presence of acetic acid. It rapidly darkens even when protected from the light. Insoluble in boiling acetic acid, it is slightly soluble in dilute mineral acids evolving hydrogen cyanide. Potassium hydroxide liberates silver oxide, potassium carbonyl ferrocyanide being simultaneously produced.