Mechanistic Studies on the Oxidation of Nitrite by a μ ‐Oxodiiron(III,III) Complex in Aqueous Acidic Media

Examined in this study is the kinetics of a net 2e − transfer between [Fe 2 ( μ ‐O)(phen) 4 (H 2 O) 2 ] 4+ ( 1 ) and its hydrolytic derivatives [Fe 2 ( μ ‐O)(phen) 4 (H 2 O)(OH)] 3+ ( 2 ) and [Fe 2 ( μ ‐O)(phen) 4 (OH) 2 ] 2+ ( 3 ) with $\rm{{{NO}}_{{2}}^ - }$ in aqueous media and in presence of excess 1,10‐phenanthroline (phen). The reaction is quantitative with a 1 : 1 stoichiometry between the oxidant and reductant to produce ferroin ([Fe(phen) 3 ] 2+ ) and $\rm{{{NO}}_{{3}}^ - }$ . The order of reactivity of the oxidant species is 1  >  2  >  3 , in agreement with the progressive cationic charge reduction. The reactions appear to be inner‐sphere where the initial one‐electron proton‐coupled redox (1e − , 1H + ; electroprotic) seems to be rate‐determining.