title: Spectroscopic capture and reactivity of a low-spin cobalt(IV)-oxo complex stabilized by binding redox-inactive metal ions.
abstract: High-valent cobalt-oxo intermediates are proposed as reactive intermediates in a number of cobalt-complex-mediated oxidation reactions. Herein we report the spectroscopic capture of low-spin (S=1/2) Co(IV)-oxo species in the presence of redox-inactive metal ions, such as Sc(3+), Ce(3+), Y(3+), and Zn(2+), and the investigation of their reactivity in C-H bond activation and sulfoxidation reactions. Theoretical calculations predict that the binding of Lewis acidic metal ions to the cobalt-oxo core increases the electrophilicity of the oxygen atom, resulting in the redox tautomerism of a highly unstable [(TAML)Co(III)(O˙)](2-) species to a more stable [(TAML)Co(IV)(O)(M(n+))] core. The present report supports the proposed role of the redox-inactive metal ions in facilitating the formation of high-valent metal-oxo cores as a necessary step for oxygen evolution in chemistry and biology.
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Seungwoo
authors.initials: S
authors.lastname: Hong
authors.affiliation: Humboldt-Universität zu Berlin, Department of Chemistry, Brook Taylor Strasse 2, 12489 Berlin, Germany.
authors.forename: Florian Felix
authors.initials: FF
authors.lastname: Pfaff
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Eunji
authors.initials: E
authors.lastname: Kwon
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Seo
authors.affiliation: Max-Plank-Institut für chemische Energiekonversion, Mülheim an der Ruhr (Germany).
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.affiliation: Humboldt-Universität zu Berlin, Department of Chemistry, Brook Taylor Strasse 2, 12489 Berlin, Germany.
authors.forename: Kallol
authors.initials: K
authors.lastname: Ray
authors.affiliation: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D056831:Coordination Complexes; D007477:Ions; D008670:Metals; D003035:Cobalt; D010100:Oxygen
keywords: Lewis acids; cobalt; oxo ligands; oxygenation; redox tautomerization
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