title: Dioxygen activation at a single copper site: structure, bonding, and mechanism of formation of 1:1 Cu-O2 adducts.
abstract: To evaluate the fundamental process of O(2) activation at a single copper site that occurs in biological and catalytic systems, a detailed study of O(2) binding to Cu(I) complexes of beta-diketiminate ligands L (L(1) = backbone Me; L(2) = backbone tBu) by X-ray crystallography, X-ray absorption spectroscopy (XAS), cryogenic stopped-flow kinetics, and theoretical calculations was performed. Using synchrotron radiation, an X-ray diffraction data set for L(2)CuO(2) was acquired, which led to structural parameters in close agreement to theoretical predictions. Significant Cu(III)-peroxo character for the complex was corroborated by XAS. On the basis of stopped-flow kinetics data and theoretical calculations for the oxygenation of L(1)Cu(RCN) (R = alkyl, aryl) in THF and THF/RCN mixtures between 193 and 233 K, a dual pathway mechanism is proposed involving (a) rate-determining solvolysis of RCN by THF followed by rapid oxygenation of L(1)Cu(THF) and (b) direct, bimolecular oxygenation of L(1)Cu(RCN) via an associative process.
authors.affiliation: Department of Chemistry, Center for Metals in Biocatalysis, and Supercomputer Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
authors.forename: Nermeen W
authors.initials: NW
authors.lastname: Aboelella
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Kryatov
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Gherman
authors.forename: William W
authors.initials: WW
authors.lastname: Brennessel
authors.forename: Victor G
authors.initials: VG
authors.lastname: Young
authors.forename: Ritimukta
authors.initials: R
authors.lastname: Sarangi
authors.forename: Elena V
authors.initials: EV
authors.lastname: Rybak-Akimova
authors.forename: Keith O
authors.initials: KO
authors.lastname: Hodgson
authors.forename: Britt
authors.initials: B
authors.lastname: Hedman
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Cramer
authors.forename: William B
authors.initials: WB
authors.lastname: Tolman
mesh_terms: D001665:Binding Sites; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007700:Kinetics; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D009942:Organometallic Compounds; D003300:Copper; D010100:Oxygen