Chromic Thiocyanate, Cr(SCN)₃

Chromic Thiocyanate, Cr(SCN)₃, is prepared by dissolving freshly precipitated chromic hydroxide in thiocyanic acid and evaporating the green-violet solution over sulphuric acid, or by concentrating a solution of chromithiocyanic acid either by heating or over sulphuric acid. It is obtained as a grey, amorphous, deliquescent mass, which readily dissolves in water to form a violet solution. When freshly prepared, the solution does not answer to the ordinary precipitation reactions for the Cr^•• and SCN' ions. However, hydrolytic dissociation gradually takes place, especially under the influence of sunlight; the solution becomes green, and precipitates are obtained with silver nitrate and ammonia solutions. It is soluble in the chief organic solvents.

Ammoniated compounds, of composition Cr(NH₃)₂(SCN)₃.H₂O; Cr(NH₃)₂(SCN)₃.2H₂O; NH₄CNS.Cr(NH₃)₂(SCN)₃; NH₄CNS. Cr(NH₃)₄(SCN)₃; Cr(NH₃)₂(SCN)₄.NH₄I, have been prepared.

Thiocyano salts of chromium with organic bases, e.g. pyridine and ethylenediamine, have also been obtained.