Mechanism of the oxidation of iron(II) by the azide radical

Abstract

The azide radical reacts with Fe2+aq at pH 5.6 to produce a coloured species which is identical to that obtained by adding ferric iron to sodium azide solution at the same pH. The rate of formation of the coloured species is independent of [Fe2+aq] and proportional to [N–3], and indicates that oxidation of Fe2+aq by N3 proceeds by rapid outer-sphere electron transfer [k(N3+ Fe2+aq) > 1.7 × 109 dm3 mol–1 s–1] followed by a rate controlling reaction between N–3 and the product FeIII[k(N–3+ FeIII)= 8.4 × 105 dm3 mol–1 s–1].