title: Photoelectron spectroscopy of doubly and singly charged group VIB dimetalate anions: M2O72-, MM'O72-, and M2O7- (M, M' = Cr, Mo, W).
abstract: We produced both doubly and singly charged Group VIB dimetalate species-M(2)O(7)(2-), MM'O(7)(2-), and M(2)O(7)(-) (M, M' = Cr, Mo, W)-using two different experimental techniques (electrospray ionization for the doubly charged anions and laser vaporization for the singly charged anions) and investigated their electronic and geometric structures using photoelectron spectroscopy and density functional calculations. Distinct changes in the electronic and geometric structures were observed as a function of the metal and charge state. The electron binding energies of the heteronuclear dianions MM'O(7)(2-) were observed to be roughly the average of those of their homonuclear counterparts (M(2)O(7)(2-) and M'(2)O(7)(2-)). Density functional calculations indicated that W(2)O(7)(2-), W(2)O(7)(-), and W(2)O(7) possess different ground-state structures: the dianion is highly symmetric (D(3d),(1)A(1g)) with a single bridging oxo ligand, the monoanion is a doublet (C(1), (2)A) with two bridging oxo ligands and a radical terminal oxo ligand, whereas the neutral is a singlet (C(1), (1)A) with two bridging oxo ligands and a terminal peroxo ligand. The combined experimental and theoretical study provides insights into the evolution of geometric and electronic structures as a function of charge state. The clusters identified might provide insights into the possible structures of reactive species present in early transition-metal oxide catalysts that are relevant to their reactivity and catalytic function.
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, WA 99354, USA.
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Zhai
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.forename: Tom
authors.initials: T
authors.lastname: Waters
authors.forename: Xue-Bin
authors.initials: XB
authors.lastname: Wang
authors.forename: Richard A J
authors.initials: RA
authors.lastname: O'Hair
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Wedd
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang
mesh_terms: D000838:Anions / Q000737:chemistry*; D002384:Catalysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D017608:Chromium Compounds / Q000737:chemistry*; D003198:Computer Simulation; D005740:Gases / Q000737:chemistry*; D007536:Isomerism; D008968:Molecular Conformation; D008982:Molybdenum / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D013057:Spectrum Analysis; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: D000838:Anions; D017608:Chromium Compounds; D005740:Gases; D010087:Oxides; D017973:Tungsten Compounds; D008982:Molybdenum