Factors affecting the addition of sulphur dioxide and nitric oxide to µ-peroxo-dicobalt(III) complexes and the reactions with µ-superoxo-complexes

Abstract

The reactions of nine µ-peroxo-dicobalt(III) complexes with gaseous SO₂, liquid SO₂, and aqueous sulphite have been investigated. Whereas double-bridged complexes (A)—(C) having more exposed O₂-bridges give µ-sulphato-products under all conditions except aqueous solutions pH > ca. 6, single-bridged complexes (D)—(H) give significant reaction only after extensive treatment with liquid SO₂. Single-bridged µ-sulphato-complexes are believed to be formed, but these readily undergo bridge cleavage in aqueous solutions. The procedure previously reported for the preparation of the µ-sulphato-complex [(NO₂)₂(NH₃)₃Co·SO₄·Co(NH₃)₃(NO₂)₂],2H₂O has been shown to give instead [Co(NH₃)₃(NO₂)₂(H₂O)]₂SO₄. Two µ-amido-µ-superoxo-complexes (J) and (K) do not react with SO₂ in the gas phase, but give the µ-amido-µ-sulphato-product with SO₂ in the liquid phase and in aqueous solution. Reactions of (A) and (J) with NO have also been investigated. In aqueous solutions complex (J) is first reduced to (A) which then gives the µ-amido-µ-nitrito-complex.