Cupric thiocyanate, Cu(CNS)₂

The Cupric thiocyanate, Cu(CNS)₂, is formed as a velvet-black precipitate by adding basic cupric carbonate or cupric hydroxide to a solution of thiocyanic acid, and by the interaction of potassium thiocyanate and concentrated solutions of cupric salts. It is very unstable, being transformed by contact with water into cuprous thiocyanate. With ammonium hydroxide it yields blue, acicular crystals of ammonio-cupric thiocyanate, Cu(CNS)₂,2NH₃, also produced by dissolving cupric hydroxide in ammonium thiocyanate.