Unusual products observed in gas-phase W{sub x}O{sub y}{sup -}+H{sub 2}O and D{sub 2}O reactions
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405 (United States)
Addition of H{sub 2}O and D{sub 2}O to small tungsten suboxide cluster anions W{sub x}O{sub y}{sup -} (x=1-4; y{<=}3x) was studied using mass spectrometric measurements from a high-pressure fast flow reactor. Within the WO{sub y}{sup -} mass manifold, which also includes WO{sub 4}H{sup -}, product masses correspond to the addition of one to three H{sub 2}O or D{sub 2}O molecules. Within the W{sub 2}O{sub y}{sup -} cluster series, product distributions suggest that sequential oxidation W{sub 2}O{sub y}{sup -}+H{sub 2}O/D{sub 2}O{yields}W{sub 2}O{sub y+1}{sup -}+H{sub 2}/D{sub 2} occurs for y<5, while for W{sub 2}O{sub 5}{sup -}, W{sub 2}O{sub 6}H{sub 2}{sup -}/W{sub 2}O{sub 6}D{sub 2}{sup -} is primarily produced. W{sub 2}O{sub 6}{sup -} does not appear reactive. For the W{sub 3}O{sub y}{sup -} cluster series, sequential oxidation with H{sub 2} and D{sub 2} production occurs for y<6, while W{sub 3}O{sub 6}{sup -} and W{sub 3}O{sub 7}{sup -} produce W{sub 3}O{sub 7}H{sub 2}{sup -}/W{sub 3}O{sub 7}D{sub 2}{sup -} and W{sub 3}O{sub 8}H{sub 2}{sup -}/W{sub 3}O{sub 8}D{sub 2}{sup -}, respectively. Lower mass resolution in the W{sub 4}O{sub y}{sup -} mass range prevents definitive product assignments, but intensity patterns suggest that sequential oxidation with H{sub 2}/D{sub 2} evolution occurs for y<6, while W{sub 4}O{sub y+1}H{sub 2}{sup -}/W{sub 4}O{sub y+1}D{sub 2}{sup -} products result from addition to W{sub 4}O{sub 6}{sup -} and W{sub 4}O{sub 7}{sup -}. Based on bond energy arguments, the H{sub 2}/D{sub 2} loss reaction is energetically favored if the new O-W{sub x}O{sub y}{sup -} bond energy is greater than 5.1 eV. The relative magnitude of the rate constants for sequential oxidation and H{sub 2}O/D{sub 2}O addition for the x=2 series was determined. There are no discernable differences in rate constants for reactions with H{sub 2}O or D{sub 2}O, suggesting that the H{sub 2} and D{sub 2} loss from the lower-oxide/hydroxide intermediates is very fast relative to the addition of H{sub 2}O or D{sub 2}O.
- OSTI ID:
- 21255544
- Journal Information:
- Journal of Chemical Physics, Vol. 130, Issue 12; Other Information: DOI: 10.1063/1.3096414; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Comparative study of water reactivity with Mo{sub 2}O{sub y}{sup −} and W{sub 2}O{sub y}{sup −} clusters: A combined experimental and theoretical investigation
Equilibria between {alpha} and {beta} isomers of Keggin heteropolytungstates