Reactions of sulfur(IV) with complex ions of chromium-, manganese-, iron- and cobalt(III) in aqueous medium

The reactions of sulfur(IV) with complexes of Cr-III, Mn-III, Fe-III and Co -III are discussed. Cr-III forms O-sulfito complexes while Mn-III and Fe-II I form S-bonded sulfito species. The oxygen bonded sulfito species of Co-II I are transient intermediates which undergo sulfite ligand linkage isomeriz ation and facile redox reactions. The S-bonded sulfito Co-III species can b e photochemically isomerized to its O-bonded isomer. The ligand control on the kinetics of reversible substitution of S-IV at Cr-III, Mn-III, Fe-III a nd Co-III centres, the redox activities and also the S-IV induced reactions of the resulting sulfito complexes are highlighted.