title: Crystallographic and spectroscopic characterization and reactivities of a mononuclear non-haem iron(III)-superoxo complex.
abstract: Mononuclear non-haem iron(III)-superoxo species (Fe(III)-O2(-·)) have been implicated as key intermediates in the catalytic cycles of dioxygen activation by non-haem iron enzymes. Although non-haem iron(III)-superoxo species have been trapped and characterized spectroscopically in enzymatic and biomimetic reactions, no structural information has yet been obtained. Here we report the isolation, spectroscopic characterization and crystal structure of a mononuclear side-on (η(2)) iron(III)-superoxo complex with a tetraamido macrocyclic ligand. The non-haem iron(III)-superoxo species undergoes both electrophilic and nucleophilic oxidation reactions, as well as O2-transfer between metal complexes. In the O2-transfer reaction, the iron(III)-superoxo complex transfers the bound O2 unit to a manganese(III) analogue, resulting in the formation of a manganese(IV)-peroxo complex, which is characterized structurally and spectroscopically as a mononuclear side-on (η(2)) manganese(IV)-peroxo complex. The difference in the redox distribution between the metal ions and O2 in iron(III)-superoxo and manganese(IV)-peroxo complexes is rationalized using density functional theory calculations.
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-ku, Seoul 120-750, Korea.
authors.forename: Seungwoo
authors.initials: S
authors.lastname: Hong
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305, USA.
authors.forename: Kyle D
authors.initials: KD
authors.lastname: Sutherlin
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-ku, Seoul 120-750, Korea.
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Park
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-ku, Seoul 120-750, Korea.
authors.forename: Eunji
authors.initials: E
authors.lastname: Kwon
authors.affiliation: Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Maxime A
authors.initials: MA
authors.lastname: Siegler
authors.affiliation: 1] Department of Chemistry, Stanford University, Stanford, California 94305, USA [2] Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Menlo Park, California 94025, USA.
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-ku, Seoul 120-750, Korea.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D006860:Hydrogen Bonding; D008024:Ligands; D047028:Macrocyclic Compounds / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011789:Quantum Theory; D013481:Superoxides / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D056831:Coordination Complexes; D005290:Ferric Compounds; D008024:Ligands; D047028:Macrocyclic Compounds; D017895:Manganese Compounds; D013481:Superoxides; D010100:Oxygen