title: Modeling biological copper clusters: synthesis of a tricopper complex, and its chloride- and sulfide-bridged congeners.
abstract: The synthesis and characterization of a family of tricopper clusters housed within a tris(β-diketimine) cyclophane ligand (H3L) that bear structural similarities to biological copper clusters are reported. In all complexes, each Cu atom is held within the N2-chelate of a single β-diketiminate arm. Reaction of L(3-) with CuCl affords an anionic complex containing a μ3-chloride donor in the central cavity, whereas there is no evidence for bromide incorporation in the product of the reaction of L(3-) with CuBr (Cu3L). Cu3L reacts with elemental sulfur to generate the corresponding air-stable mixed-valent (μ3-sulfido)tricopper complex, Cu3(μ3-S)L, which represents the first example of a sulfide-bridged copper cluster in which each metal center is both coordinatively unsaturated and held within a N-rich environment. The calculated LUMO is predominantly Cu-S π* in character and delocalized over all three metal centers, which is consistent with the isotropic ten-line absorption (g ∼ 2.095, A ∼ 33 G) observed at room temperature in EPR spectra of the one-electron chemically reduced complex, [Cu3(μ3-S)L](-).
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida , Gainesville, Florida 32611-7200, United States.
authors.forename: Gianna N
authors.initials: GN
authors.lastname: Di Francesco
authors.forename: Aleth
authors.initials: A
authors.lastname: Gaillard
authors.forename: Ion
authors.initials: I
authors.lastname: Ghiviriga
authors.forename: Khalil A
authors.initials: KA
authors.lastname: Abboud
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Murray
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D008958:Models, Molecular; D013440:Sulfides / Q000737:chemistry*
chemical_list: D002712:Chlorides; D013440:Sulfides; D003300:Copper