Dioxygen Activation and Catalytic Reduction to Hydrogen Peroxide by a Thiolate-Bridged Dimanganese(II) Complex with a Pendant Thiol
† CNRS UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France
‡ INAC-SCIB, Université Grenoble Alpes, F-38000 Grenoble, France
⊥ Reconnaissance Ionique et Chimie de Coordination, CEA, INAC-SCIB, F-38000 Grenoble, France
§ Metalloproteins Unit, Institut de Biologie Structurale Jean-Pierre Ebel, CEA, CNRS UMR 5075, Université Grenoble Alpes, 41 rue Horowitz, 38027 Grenoble Cedex 1, France
∥ Université de Lyon, F-69622 Lyon, France
# Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France
∇ CNRS, UMR 5086 Bases Moléculaires et Structurales de Systèmes Infectieux, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, F-69367 Lyon, France
⊗ Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr,Germany
× Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
¶ CNRS, CRPP, UPR 8641, F-33600 Pessac, France
▲ CRPP, UPR 8641, Université Bordeaux, F-33600 Pessac, France
J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/jacs.5b04917
Publication Date (Web): June 15, 2015
Copyright © 2015 American Chemical Society
Abstract
Herein, we describe an uncommon example of a manganese–thiolate complex, which is capable of activating dioxygen and catalyzing its two-electron reduction to generate H2O2. The structurally characterized dimercapto-bridged MnII dimer [MnII2(LS)(LSH)]ClO4 (MnII2SH) is formed by reaction of the LS ligand (2,2′-(2,2′-bipyridine-6,6′-diyl)bis(1,1-diphenylethanethiolate)) with MnII. The unusual presence of a pendant thiol group bound to one MnII ion in MnII2SH is evidenced both in the solid state and in solution. The MnII2SH complex reacts with dioxygen in CH3CN, leading to the formation of a rare mono-μ-hydroxo dinuclear MnIII complex, [(MnIII2(LS)2(OH)]ClO4 (MnIII2OH), which has also been structurally characterized. When MnII2SH reacts with O2 in the presence of a proton source, 2,6-lutidinium tetrafluoroborate (up to 50 equiv), the formation of a new Mn species is observed, assigned to a bis-μ-thiolato dinuclear MnIII complex with two terminal thiolate groups (MnIII2), with the concomitant production of H2O2 up to ∼40% vs MnII2SH. The addition of a catalytic amount ofMnII2SH to an air-saturated solution of MenFc (n = 8 or 10) and 2,6-lutidinium tetrafluoroborate results in the quantitative and efficient oxidation of MenFc by O2 to afford the respective ferrocenium derivatives (MenFc+, with n = 8 or 10). Hydrogen peroxide is mainly produced during the catalytic reduction of dioxygen with 80–84% selectivity, making the MnII2SH complex a rare Mn-based active catalyst for two-electron O2 reduction.
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