| Abstract
| - Spectroscopic evidence is presented for theoperation of a multistep mechanism during the interaction of[FeII(edta)] with molecular oxygen in aqueoussolution. The mechanism consists of subsequent ligand substitution andelectron-transfer reactions, which, in the presence of an excess of[FeII(edta)], involve the formation of aperoxo-bridged dimeric species.
- A detailed mechanistic study of the reaction of[FeII(edta)] (edta = ethylenediaminetetraacetate)with molecularoxygen was conducted and the oxidation kinetics were investigated as afunction of [FeII], [O2], pH,temperature,and pressure. The observed kinetic data in the presence of anexcess of [FeII(edta)] can be accounted for intermsof a four-step mechanism: reaction of (I)[FeII(edta)H2O]2-with O2 by a substitution-controlled process toform[FeII(edta)O2]2-;(II) electron transfer to form an FeIII−superoxo species;(III) subsequent substitution on a second[FeII(edta)H2O]2-anion followed by electron transfer to give[FeIII(edta)−O22-−FeIII(edta)]4-;and (IV) a fastdecomposition yielding the monomeric[FeIII(edta)]- andH2O2, which rapidly reacts with[FeII(edta)]. Rate andactivation parameters for some of these steps are reported anddiscussed with reference to available literaturedata.
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