Standard electrode potentials involving radicals in aqueous solution: inorganic radicals (IUPAC Technical Report)

Abstract

Abstract:Recommendations are made for standard potentials involving select inorganic radicals in aqueous solution at 25 °C. These recommendations are based on a critical and thorough literature review and also by performing derivations from various literature reports. The recommended data are summarized in tables of standard potentials, Gibbs energies of formation, radical pK a 's, and hemicolligation equilibrium constants. In all cases, current best estimates of the uncertainties are provided. An extensive set of Data Sheets is appended that provide original literature references, summarize the experimental results, and describe the decisions and procedures leading to each of the recommendations.

Mechanistic Studies on the Role of [CuII(CO3)n]2−2n as a Water Oxidation Catalyst: Carbonate as a Non‐Innocent Ligand

“…The carbonate radical anion is a strong single‐electron oxidant with a redox potential of 1.76 V versus NHE at pH 7.0 and 1.57 V versus NHE at pH 12.0 . When N 2 O saturated solutions containing {Cu II (HCO 3 ) m (CO 3 ) n 2−2 n − m } aq (for simplicity in the following the equations will be written, {Cu II (CO 3 ) n 2−2 n } aq without the ligated bicarbonate) are irradiated, three consecutive reactions are observed.…”

Formal Reduction Potentials of Difluorotyrosine and Trifluorotyrosine Protein Residues: Defining the Thermodynamics of Multistep Radical Transfer

“…Additionally, some of the reference potentials used in the older literature were not as well-determined as they are today. 56 Aqueous Y gives rise to irreversible voltammograms since Y–O• dimerization is fast ( k dim 2–7 × 10 8 M −1 s −1 ) 29,57 relative to the experimental time scale. These voltammograms, which display only an anodic wave, may reflect a reversible, quasi-reversible or irreversible electrode reaction.…”

“…58,59 Harriman 53 and DeFelippis et al 54 applied this approach but unfortunately used an incorrect equation to compensate for k dim . 46 Recently reported (or recommended) pH 7.0 potentials for aqueous Y are 0.93 ± 0.02 V, 52 0.91 ± 0.02 V, 56 and 0.96 V. 46 We therefore take a consensus value of 920–940 ± 20 mV for the aqueous Y(O•/OH) redox couple at pH 7.0. E °′ of Y 32 (O•/OH) is 986 ± 3 mV at pH 7.0 (Figure 5; Table S2).…”

Activation of dioxygen by copper metalloproteins and insights from model complexes

“…Reduction potentials can be found in Ref. [7]. Copper-containing enzymes that perform parts of this reduction are shown…”

“…This process is well known in aqueous systems and proceeds through various intermediates including superoxide ( ${\mathrm{normalO}}_2^{·-}$), hydrogen peroxide (H 2 O 2 ), and hydroxyl radical ( · OH); two equivalents of water are produced from this reaction (Scheme 1) [4–7]. However, it is also important to know how these processes occur in the presence of metal ions, as many important oxidative transformations have been attributed to various reactive metal–oxygen species [3, 8–11].…”