O−O Bond Formation and Liberation of Dioxygen Mediated by N5‐Coordinate Non‐Heme Iron(IV) Complexes |
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Authors: | Nicole Kroll Ina Speckmann Marc Schoknecht Jana Gülzow Marek Diekmann Johannes Pfrommer Anika Stritt Maria Schlangen Andreas Grohmann Gerald Hrner |
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Institution: | Nicole Kroll,Ina Speckmann,Marc Schoknecht,Jana Gülzow,Marek Diekmann,Johannes Pfrommer,Anika Stritt,Maria Schlangen,Andreas Grohmann,Gerald Hörner |
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Abstract: | Formation of the O?O bond is considered the critical step in oxidative water cleavage to produce dioxygen. High‐valent metal complexes with terminal oxo (oxido) ligands are commonly regarded as instrumental for oxygen evolution, but direct experimental evidence is lacking. Herein, we describe the formation of the O?O bond in solution, from non‐heme, N5‐coordinate oxoiron(IV) species. Oxygen evolution from oxoiron(IV) is instantaneous once meta‐chloroperbenzoic acid is administered in excess. Oxygen‐isotope labeling reveals two sources of dioxygen, pointing to mechanistic branching between HAT (hydrogen atom transfer)‐initiated free‐radical pathways of the peroxides, which are typical of catalase‐like reactivity, and iron‐borne O?O coupling, which is unprecedented for non‐heme/peroxide systems. Interpretation in terms of FeIV(O)] and FeV(O)] being the resting and active principles of the O?O coupling, respectively, concurs with fundamental mechanistic ideas of (electro‐) chemical O?O coupling in water oxidation catalysis (WOC), indicating that central mechanistic motifs of WOC can be mimicked in a catalase/peroxidase setting. |
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Keywords: | Bioanorganische Chemie Eisen Stickstoffliganden O-O-Aktivierung Oxoliganden |
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