CO2-CATALYZED ONE-ELECTRON OXIDATIONS BY PEROXYNITRITE - PROPERTIES OF THE REACTIVE INTERMEDIATE

In neutral bicarbonate-containing solutions, the predominant pathway f or peroxynitrite decomposition was CO2-catalyzed formation of nitrate ion; that is, CO2 was regenerated in the process. When nitrite ion was present, HCO3- also formed during ONO2- decomposition. The data could be reproduced by a kinetic model wherein a reactive intermediate form ed from ONO2- and CO2 oxidizes NO2- to . NO2, which subsequently hydro lyzes in a bimolecular reaction to form NO3- and regenerate NO2-. Carb on dioxide catalyzed one-electron oxidations of Fe(CN)(6)(4-), Mo(CN)( 8)(4-), Os(bpy)(3)(2+), Fe(bpy)(3)(2+), Ru(bpy)(2+), and I- were also observed, establishing that the reactive intermediate is capable of ox idizing compounds whose reduction potentials are as great as 1.3 V. Th e maximal product yields, measured for reactions with NO2-, Fe(CN)(6)( 4-), and Mo(CN)(8)(4-), were all similar to 35% of the added peroxynit rite, suggesting that they were oxidized by a common intermediate. On the basis of the reactivity characteristics revealed, the intermediate is suggested to be carbonate radical formed by homolytic decompositio n of an ONO2CO2- adduct.