title: Evidence for an oxygen evolving iron-oxo-cerium intermediate in iron-catalysed water oxidation.
abstract: The non-haem iron complex α-[Fe(II)(CF3SO3)2(mcp)] (mcp=(N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)-1,2-cis-diaminocyclohexane) reacts with Ce(IV) to oxidize water to O2, representing an iron-based functional model for the oxygen evolving complex of photosystem II. Here we trap an intermediate, characterized by cryospray ionization high resolution mass spectrometry and resonance Raman spectroscopy, and formulated as [(mcp)Fe(IV)(O)(μ-O)Ce(IV)(NO3)3](+), the first example of a well-characterized inner-sphere complex to be formed in cerium(IV)-mediated water oxidation. The identification of this reactive Fe(IV)-O-Ce(IV) adduct may open new pathways to validate mechanistic notions of an analogous Mn(V)-O-Ca(II) unit in the oxygen evolving complex that is responsible for carrying out the key O-O bond forming step.
authors.affiliation: Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Zoel
authors.initials: Z
authors.lastname: Codolà
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant St S.E., Minneapolis, Minnesota 55455, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez
authors.affiliation: Serveis Tècnics de Recerca (STR), Parc Cientific i Tecnològic, Universitat de Girona, 17003 Girona, Spain.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Kleespies
authors.affiliation: Serveis Tècnics de Recerca (STR), Parc Cientific i Tecnològic, Universitat de Girona, 17003 Girona, Spain.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
authors.affiliation: Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Costas
authors.affiliation: Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Lloret-Fillol
mesh_terms: D001419:Bacteria / Q000378:metabolism; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods; D010100:Oxygen / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D045332:Photosystem II Protein Complex; D014867:Water; D002563:Cerium; D007501:Iron; D010100:Oxygen