Oxidation of Metal Ion Complexes

Spectrophotometric and potentiometric techniques have been used to study the Fe(II)- NOi reaction at high acidity [0.6-2.0 M (H )]. The overall reaction  

Complex side reactions have been eliminated in the corresponding reaction with iodate by the presence of CH2 CHCH20H, which reacts very rapidly with the iodine(I) formed. The overall reaction is given in equation (44), 

Rate-determining steps leading to I(IV) and I(III) are postulated, with subsequent rapid reduction of intermediate iodine species. An induction period followed by oxidation of the [Fe(phen)3] complex is a feature of the reaction of that complex with bromate ions. The rates of the corresponding reactions with CI2 and affected by Cl , Br , or hydrogen ion. The oxidations occur via the one-electron transfer steps and an analysis of the data and those for other metal ion reductants has been made using a Marcus theory approach. The kinetics of the peroxodisulfate oxidation of two [Fe(II)(a-diimine)3] complexes have been investigated in binary aqueous-solvent mixtures.The rate data have been dissected into initial and transition state energies. Comparisons between the relative contributions to these parameters for redox and substitution reactions remain a topic of interest. 

In the presence of excess HNO3, the rate of oxidation of [Fe(CN)6] by HNO2 is independent of the initial iron(II) complex concentration.At low [H ] ( 0.01 M) the rates are first order with respect to the reaction 

The kinetics of triplet methylene blue quenching by various iron(II) complexes including [Fe(OH2)6], [Fe(CN)6], and [Fe(bipy)3] have been studied at different pH s. The reactions are redox controlled and the rates of the reverse electron transfer have also been determined. The properties of the outer-sphere charge transfer band in the ion pair [Fe(CN)6 (PQ = 1,1 - 

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