Potassium Iridium Sulphite, K₃Ir(SO₃)₃

Potassium Iridium Sulphite, 3K₂SO₃.Ir₂(SO₃)₃.6H₂O, which may be written as K₃Ir(SO₃)₃.3H₂O, to show an analogy with the constitutions of the iridi-nitrites and iridi-eyanides described in the sequel. The salt is obtained as a brown, crystalline, insoluble mass on adding potassium carbonate to a solution of iridium sulphite.

Closely resembling the foregoing salt is the ammonium derivative, 3(NH₄)₂SO₃.Ir₂(SO₃)₃.3H₂O. The complex chlor-sulphites:

2K₂SO₃.IrCl.SO₃, 3KCl.Ir₂SO₃.IrCl₂.SO₃.2H₂O, 2K₂SO₃.KSO₃.IrCl₂.2KCl.12H₂O, and IrCl₂.4NH₄Cl.H₂SO₃

have also been prepared.

Sodium yields a sulphite, of formula 3Na₂SO₃.Ir₂(SO₃)₃.8H₂O, obtained in a similar manner to the ammonium and potassium salts. An acid sulphite, 3Na₂SO₃.H₂SO₃.IrSO₃.Aq., and a neutral sulphite of formula 3Na₂SO₃.IrSO₃.10H₂O, have been described. It is difficult to believe, however, that many of the foregoing complexes are definite chemical entities.