Due to the usefulness of small transition metal oxide clusters as models for bulk metal oxide defect sites, and the role of defect sites in catalysis, interest in the reactivity of small molecules, such as CH4, H2O, and alcohols, with these model systems has grown.  Reactions between small molybdenum and tungsten oxide cluster anions, MxOy- (M = 98Mo, 186W; x = 1-3, y = 3x), and methanol (CH3OH) have been studied using mass spectrometric analysis of products formed in a high-pressure, fast-flow reactor.  Due to the mass coincidence of methanol and two oxygen atoms, anion photoelectron spectroscopy was also used to interrogate the products in order to distinguish oxidation products from methanol addition products.  Product distributions vary with the number of metal atoms in the cluster. Within all manifolds, the addition of methanol skews oxide distributions towards higher masses, and hydrides are formed or become more prominent. In the cases of both mono-Mo and W manifolds, the heaviest mass assigned corresponds to the product of MO2- + 2CH3OH ? MO4C2H6- + H2.  For the x = 2 manifolds, sequential oxidation appears to occur for y = 2-5. Ions that are mass coincident with either M2O7- or M2O5CH3OH- appear to be the terminal product in this series of reactions. Similarly, the x = 3 manifold exhibits sequential oxidation for y = 3-8, and ions mass coincident with either M3O10- or M3O8CH3OH- appear to be the terminal product of these manifolds.  Generally, sequential oxidation processes are seen when methanol reacts with small molybdenum and tungsten oxide cluster anions. Similar sequential oxidation processes were seen in previous reactivity studies between molybdenum and tungsten oxide cluster anions with D2O, with the exception of the Mo2Oy- series, which truncates at Mo2O6D2-.

Methanol reactivity with small molybdenum and tungsten oxide cluster anions

246th National Meeting (2013)

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