The electron transfer reactions of Mo(CN)₈⁴, W(CN)₈⁴⁻ and Fe(CN)₆⁴⁻ with the manganese (III) complex oftrans-cyclohexane-1,2-diamine-N,N,N′,N′-tetraacetic acid have been studied by stopped-flow spectrophotometry in the pH range 2.0–6.5. Analysis of kinetic data conforms to an outer-sphere process in each case. The validity of Marcus’ crossreaction relation to these reactions is fairly satisfactory.

The kinetics of the reduction of [Ni^III(L¹)]²⁺ (where HL¹ = 15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-en-2-one oxime) by sulphur(IV) and selenium (IV) over the regions pH 2.50–8.02 and 2.01–4.00 respectively have been investigated at 30°C. Attempts were made to evaluate the reactivity of all the reacting species, of sulphur(IV) and selenium(IV) by considering suitable pH ranges. The oxidation of SC₂·H₂O and HSO₃⁻ is proposed to proceed through the formation of a hydrogen-bonded adduct. The reaction with SO₃²⁻ seems to follow a direct outer-sphere route which is well supported by Marcus crossrelation calculation. The oxidation of HSeO_l3⁻ is ≈ 10³ times slower than that of H₂SeO₃. The kinetic data indicate that the oxidation of sulphur(IV) by [Ni^IIIL¹)]²⁺ is much more favourable as compared to the corresponding oxidation of selenium(IV).