Ruthenium Sesquisulphite, Ru₂(SO₃)₃

Ruthenium Sesquisulphite, Ru₂(SO₃)₃, is obtained by passing sulphur dioxide through a solution of the sulphate whereby the colour changes from bright red through green to blue. Addition of alcohol precipitates the sulphite in a blue colloidal form which may be dried at 80° C. It dissolves in excess of water, giving a solution from which it may be precipitated by addition of a salt. Double salts with the sulphites of potassium and sodium respectively have been prepared.

Thus, on boiling solutions of sodium chlor-ruthenite, Na₂RuCl₅, and sodium sulphite, a minute crystalline precipitate of sodium ruthenium sulphite, Na₇Ru(SO₃)₅.2H₂O, is obtained. The corresponding potassium salt has also been isolated. This, with potassium hydroxide solution is converted into the complex O[Ru(SO₃)₄K₆]₂.4H₂O. The following salts have also been obtained, O[Ru(SO₃)₂(NO)Na₂].2H₂O, and O[Ru(SO₃)₂(NO)K₂].2H₂O, both in crystalline form.