Chromium(II) chemistry. Part IV. Double sulphates

Abstract

The double salts M₂SO₄,CrSO₄,6H₂O (M = NH₄, Rb, or Cs) have been found to be high-spin compounds which obey the Curie law. Their spectroscopic and thermal properties are compatible with a tetragonally-distorted, octahedral arrangement of water molecules about the chromium(II) ion. The compounds M₂SO₃,M₂SO₄,2H₂O M = Na or K) have similar properties, but are more distorted because sulphato-groups are present. The corresponding caesium dihydrate is almost diamagnetic, and this and its spectroscopic properties are consistent with a sulphato-bridged binuclear structure like that of chromium(II) acetate monohydrate.