Cupric iodide, CuI₂

The Cupric iodide, CuI₂ is formed in solution by the interaction of cuprous iodide and iodine solution, but it has not been isolated in the solid state, as it decomposes readily into cuprous iodide and iodine. The solution is greenish-blue. Ammonia converts cupric iodide into a stable cuprammonium salt, CuI₂,4NH₃,H₂O, prepared more readily by exposure of ammoniacal cuprous iodide to air. A compound of the formula 2CuI,CuI₂,4NH₃ is also known, and crystallizes in brilliant-green needles, insoluble in water, but soluble in an aqueous solution of ammonia.