A Functional Model for the Rieske Center: Full Characterization of a Biomimetic N‐Ligated [2Fe‐2S] Cluster in Different Protonation States

: Give and take both: A bis(benzimidazolate)-capped biomimetic [2Fe-2S] cluster has been characterized in different protonation states, both in the diferric and mixed-valent forms. Protonation does not lead to structural changes of the [2Fe-2S] core, but facilitates its reduction and causes pronounced valence localization in the mixed-valent state. Concerted proton and electron transfer back to the diferric cluster emulates a key step in the function of mitochondrial Rieske proteins (see scheme).