Kinetics and mechanism of reduction of (trans-cyclohexane-1,2-diyldinitrilotetraacetato)manganese(III) by HONH(SO3)– and HON(SO3)22–

Abstract

The kinetics and mechanism of the reduction of (trans-cyclohexane-1,2-diyldinitrilotetraacetato)manganese(III) by the sulfur–nitrogen oxides HONH(SO₃)^– and HON(SO₃)₂^2– in aqueous solution were studied as a function of pH, SN oxide concentration, temperature and pressure. The kinetic data could be interpreted in terms of an inner-sphere electron-transfer mechanism. The two consecutive reaction steps observed at neutral pH were interpreted in terms of rate-determining co-ordination steps that precede the electron-transfer process. Ion chromatographic analyses of the redox products showed that the SN oxides undergo Mn^III-catalysed hydrolysis and oxidation reactions. The results are interpreted and discussed in reference to available literature data.