title: Intramolecular Electron Transfers Thwart Bistability in a Pentanuclear Iron Complex.
abstract: With the intention to investigate the redox properties of polynuclear complexes as previously reported for the pentamanganese complex [{Mn(II)(μ-bpp)3}2Mn(III)Mn(II)2(μ3-O)](3+) (2(3+)), we focused on the analogous pentairon complex that was previously isolated as all-ferrous. As Masaoka and co-workers recently published, aerobic synthesis leads to the [{Fe(II)(μ-bpp)3}2Fe(III)Fe(II)2(μ3-O)](3+) complex (1(3+)). This species exhibits in acetonitrile solution four reversible one-electron oxidation waves. Accordingly, the three oxidized species 1(4+), 1(5+), and 1(6+) with a 3Fe(II)2Fe(III), 2Fe(II)3Fe(III), and 1Fe(II)4Fe(III) composition, respectively, were generated by bulk electrolysis and isolated. Mössbauer spectroscopy allowed us to determine the spin states of all the iron ions and to unambiguously locate the sites of the successive oxidations. They all occur in the μ3-oxo core except for the 1(4+) to 1(5+) process that presents a striking electronic rearrangement, with both metals in axial position being oxidized while the core is reduced to the [Fe(III)Fe(II)2(μ3-O)](5+) oxidation level. This strongly differs from the redox behavior of the Mn5 system. The origin of this electronic switch is discussed.
authors.affiliation: Université Grenoble Alpes, DCM, F-38000 Grenoble, France.|CNRS, DCM, F-38000 Grenoble, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Gouré
authors.affiliation: Université Grenoble Alpes, DCM, F-38000 Grenoble, France.|CNRS, DCM, F-38000 Grenoble, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Gerey
authors.affiliation: Université Grenoble Alpes, LCBM, pmb, F-38000 Grenoble, France.|CEA, BIG-LCBM, pmb, F-38000 Grenoble, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Clémancey
authors.affiliation: Université Grenoble Alpes, INAC-SyMMES, F-38000 Grenoble, France.|CEA, INAC-SyMMES, Reconnaissance Ionique et Chimie de Coordination, F-38000 Grenoble, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Pécaut
authors.affiliation: Université Grenoble Alpes, DCM, F-38000 Grenoble, France.|CNRS, DCM, F-38000 Grenoble, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Molton
authors.affiliation: CEA, BIG-LCBM, pmb, F-38000 Grenoble, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Latour
authors.affiliation: CEA, BIG-LCBM, pmb, F-38000 Grenoble, France.|CNRS UMR 5249, LCBM, pmb, F-38000 Grenoble, France.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Blondin
authors.affiliation: Université Grenoble Alpes, DCM, F-38000 Grenoble, France.|CNRS, DCM, F-38000 Grenoble, France.
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Collomb