title: Multifrequency EPR and redox reactivity investigations of a bis(mu-thiolato)-dicopper(II,II) complex.
abstract: From a new tripodal ligand [N2SS'H] with mixed N, S(thioether), and S(thiolate) donor set, the corresponding bis(mu-thiolato)dicopper(II) complex has been prepared and characterized. X-ray crystallographic analysis of the complex [Cu2(N2SS')2](ClO4)2.C4H10O (1) demonstrates that the two five-coordinated Cu atoms are bridged by two thiolates leading to a nearly planar Cu2S2 core with a Cu1...Cu1* distance of 3.418(8) A and a large bridging angle Cu1S1Cu1* of 94.92 degrees. X-band (10 GHz), Q-band (34 GHz), and F-Band (115 GHz) EPR spectra of 1 are consistent with a weakly coupled dicopper(II,II) center attributed to an S = 1 state. Simulations for the three frequencies are obtained with a unique set of electronic parameters. The mean values of the spin Hamiltonian parameters for 1 are D = 0.210(3) cm(-1), E = 0.0295(5) cm(-1), |E/D| = 0.140, gx = 2.030(2), gy = 2.032(2), gz = 2.128(2). The electrochemical one-electron reduction of 1 generates the mixed-valent CuIICuI species. EPR and UV-vis spectra are consistent with a type I localized mixed-valent species, while dinuclear CuA centers of native cytochrome c oxidase (CcO)1-3 or nitrous oxide reductase (N2OR)4 have a delocalized CuIICuI mixed-valent state. After reoxidation of the CuIICuI species, the initial complex 1 is regenerated through a reversible interconversion process.
authors.affiliation: Laboratoire de Chimie Biomimétique, UMR CNRS 5616, ICMG FR CNRS 2607, BP 53X, 38041 Grenoble Cedex 9, France.
authors.forename: Wassim
authors.initials: W
authors.lastname: Rammal
authors.forename: Catherine
authors.initials: C
authors.lastname: Belle
authors.forename: Claude
authors.initials: C
authors.lastname: Béguin
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc
authors.forename: Christian
authors.initials: C
authors.lastname: Philouze
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Pierre
authors.forename: Laurent
authors.initials: L
authors.lastname: Le Pape
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bertaina
authors.forename: Eric
authors.initials: E
authors.lastname: Saint-Aman
authors.forename: Stéphane
authors.initials: S
authors.lastname: Torelli
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D003300:Copper; D010088:Oxidoreductases; C022763:nitrous oxide reductase; D003576:Electron Transport Complex IV