title: Dioxygen Activation and Catalytic Reduction to Hydrogen Peroxide by a Thiolate-Bridged Dimanganese(II) Complex with a Pendant Thiol.
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 Mn(II) dimer [Mn(II)2(LS)(LSH)]ClO4 (Mn(II)2SH) is formed by reaction of the LS ligand (2,2'-(2,2'-bipyridine-6,6'-diyl)bis(1,1-diphenylethanethiolate)) with Mn(II). The unusual presence of a pendant thiol group bound to one Mn(II) ion in Mn(II)2SH is evidenced both in the solid state and in solution. The Mn(II)2SH complex reacts with dioxygen in CH3CN, leading to the formation of a rare mono-μ-hydroxo dinuclear Mn(III) complex, [(Mn(III)2(LS)2(OH)]ClO4 (Mn(III)2OH), which has also been structurally characterized. When Mn(II)2SH 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 Mn(III) complex with two terminal thiolate groups (Mn(III)2), with the concomitant production of H2O2 up to ∼40% vs Mn(II)2SH. The addition of a catalytic amount of Mn(II)2SH 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 Mn(II)2SH complex a rare Mn-based active catalyst for two-electron O2 reduction.
authors.affiliation: †CNRS UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France.
authors.forename: Marcello
authors.initials: M
authors.lastname: Gennari
authors.affiliation: †CNRS UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France.
authors.forename: Deborah
authors.initials: D
authors.lastname: Brazzolotto
authors.affiliation: ‡INAC-SCIB, Université Grenoble Alpes, F-38000 Grenoble, France.|⊥Reconnaissance Ionique et Chimie de Coordination, CEA, INAC-SCIB, F-38000 Grenoble, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Pécaut
authors.affiliation: §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.
authors.forename: Mickael V
authors.initials: MV
authors.lastname: Cherrier
authors.affiliation: ⊗Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pollock
authors.affiliation: ⊗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.
authors.forename: Serena
authors.initials: S
authors.lastname: DeBeer
authors.affiliation: ⊗Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Retegan
authors.affiliation: ⊗Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Pantazis
authors.affiliation: ⊗Max-Planck-Institut für Chemische Energie Konversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Neese
authors.affiliation: ¶CNRS, CRPP, UPR 8641, F-33600 Pessac, France.|▲CRPP, UPR 8641, Université Bordeaux, F-33600 Pessac, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Rouzières
authors.affiliation: ¶CNRS, CRPP, UPR 8641, F-33600 Pessac, France.|▲CRPP, UPR 8641, Université Bordeaux, F-33600 Pessac, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
authors.affiliation: †CNRS UMR 5250, DCM, Université Grenoble Alpes, F-38000 Grenoble, France.
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc