Figure 2.

Transformations between various pools of Fe as mediated by ${\text{O}}_2^{-*}$. (A) Polynuclear complexes, which contain multiple Fe atoms and may also contain other inorganic and organic ligands. (B) Mononuclear inorganic complexes. (C) Mononuclear organic complexes. Fe(III) in all pools may be reduced by the ${\text{O}}_2^{-}$ anion to Fe(II), while Fe(II) in all pools may be oxidized to Fe(III) primarily by $\text{HO}{\text{O}}^{\bullet },$ but also indirectly by ${\text{O}}_2^{-}.$ The dotted arrows denote the dissociative reduction (DR) pathway, while the dashed arrows denote the non-dissociative reduction (NDR) pathway for Fe(III) reduction by ${\text{O}}_2^{-*}.$