title: Coordination and solvation of the Au+ cation: infrared photodissociation spectroscopy of mass-selected Au(H2O)n+ (n = 1-8) complexes.
abstract: Gold cation-water complexes with attached argon atoms are produced via a laser vaporization supersonic cluster source. The [Au(H(2)O)(n)Ar(x)](+) (n = 1-8; x = 1 or 2) complexes are each mass selected and studied by infrared photodissociation spectroscopy in the OH stretching frequency region to explore the coordination and solvation structures of the Au(+) cation. Density functional calculations have been performed, and the calculated vibrational spectra are compared to the experimental spectra to identify the gas-phase structures of the Au(H(2)O)(n)(+) complexes. Confirming previous theoretical predications, the first coordination shell of the Au(+) cation contains two water molecules forming a linear O-Au(+)-O arrangement; subsequent water molecules bind to the two H(2)O ligands of the Au(H(2)O)(2)(+) core ion via hydrogen bond forming of the second hydration shell, which is complete at n = 6. For the complexes with n ≤ 7, the experimental spectrum can in general be assigned to the predicted global minimum structure. However, the spectrum suggests that two or more conformers coexist for the n = 8 complex, indicating that the identification of a single global minimum becomes less important upon increasing the number of solvating water molecules.
authors.affiliation: Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai 200433, China.
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Li
authors.forename: Guanjun
authors.initials: G
authors.lastname: Wang
authors.forename: Caixia
authors.initials: C
authors.lastname: Wang
authors.forename: Mingfei
authors.initials: M
authors.lastname: Zhou
mesh_terms: D002412:Cations / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D055668:Photochemical Processes; D012995:Solubility; D013055:Spectrophotometry, Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D002412:Cations; D014867:Water; D006046:Gold