Zinc Tungstocyanide, Zn₂[W(CN)₈]

Zinc Tungstocyanide, Zn₂[W(CN)₈].4H₂O, is prepared by precipitation from a solution of the potassium salt. It is insoluble in water and acids. When heated, it loses all its water at 130° C. It dissolves in a hot solution of ammonia, forming the ammine salt, [Zn(NH₃)₃]₂[W(CN)₈], which separates on cooling. This compound loses all its ammonia on exposure to air.

Besides the salts described above, many other metals - for example, iron, mercury, copper, cobalt, and nickel - yield precipitates with soluble tungstocyanides, which, however, have not yet been fully investigated. Aluminium, bismuth, and tin do not yield such precipitates.