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Volumn 47, Issue 10, 2008, Pages 1946-1950

Activation of methane by oligomeric (Al2O3) x+ (x=3,4,5): The role of oxygen-centered radicals in thermal hydrogen-atom abstraction

Author keywords

Aluminum oxide; C H activation; Density functional calculations; Mass spectrometry; Methane

Indexed keywords

ACTIVATED ALUMINA; ALUMINA; CHEMICAL BONDS; CHEMICAL REACTIONS; METHANE;

EID: 53549113332     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200704791     Document Type: Article
Times cited : (169)

References (51)
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    • .+: Here, the bonding blocks contain one filled σ orbital, two filled π orbitals, and two singly occupied π* orbitals, resulting in high-spin situations. For further information, see: S. Shaik, M. Filatov, D. Schröder, H. Schwarz, Chem. Eur. J. 1998, 4, 193.
    • .+: Here, the bonding blocks contain one filled σ orbital, two filled π orbitals, and two singly occupied π* orbitals, resulting in high-spin situations. For further information, see: S. Shaik, M. Filatov, D. Schröder, H. Schwarz, Chem. Eur. J. 1998, 4, 193.
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    • .+ corresponds to a high-valent diradicaloid cation exhibiting also a high spin density at the oxygen atom; see also references [6] and [12].
    • .+ corresponds to a high-valent diradicaloid cation exhibiting also a high spin density at the oxygen atom; see also references [6] and [12].
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    • This view is also supported by a computational study of the closed-shell system CaO/CH4. While H-atom abstraction is slightly exothermic, the barrier of the process is huge: H.-Q. Yang, C. W. Hu, S. Qin, Chem. Phys. 2006, 330, 343
    • 4. While H-atom abstraction is slightly exothermic, the barrier of the process is huge: H.-Q. Yang, C. W. Hu, S. Qin, Chem. Phys. 2006, 330, 343.
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    • 2 needs to be added to obtain the C-H binding energy in methane.
    • 2 needs to be added to obtain the C-H binding energy in methane.
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    • In Figure 2a, it cannot be distinguished between H-abstraction from CH4 or any other impurity in the cell. Although Figure 2b shows adduct formation with water, the conceivable uptake of a hydrogen atom from water to form Al8O11OH, can be rejected on thermochemical grounds and experimental evidence. Furthermore, the rate constant of the hydrogen addition is so small that any impurity present at an absolute pressure of 1.0 × 10-10 mbar which reacts with collision rate may be the origin of the Δm=+1 product
    • -10 mbar which reacts with collision rate may be the origin of the Δm=+1 product.
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    • The structure is a true saddle point on the PES: the gradients are zero, and frequency calculation yields one imaginary frequency with a corresponding mode that consists mainly of motion of the interacting hydrogen atom
    • The structure is a true saddle point on the PES: the gradients are zero, and frequency calculation yields one imaginary frequency with a corresponding mode that consists mainly of motion of the interacting hydrogen atom.
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    • 4 is not orbiting the cluster before the collision. Previously it has been shown that the Langevin capture cross-section is smaller than the physical dimensions of the cluster for a large fraction of the neutral collision partners. Only a very small fraction of neutral molecules is actually captured by the charge; the vast majority undergo direct impact on the cluster surface. See: G. Kummerlöwe, M. K. Beyer, Int. J. Mass Spectrom. 2005, 244, 84.
    • 4 is not orbiting the cluster before the collision. Previously it has been shown that the Langevin capture cross-section is smaller than the physical dimensions of the cluster for a large fraction of the neutral collision partners. Only a very small fraction of neutral molecules is actually captured by the charge; the vast majority undergo direct impact on the cluster surface. See: G. Kummerlöwe, M. K. Beyer, Int. J. Mass Spectrom. 2005, 244, 84.
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    • Note added in proof (January 16, 2008): In a recent publication, odd/even electron alternations were reported for the gas-phase reactions of oxygen with aluminum-based cluster ions: A. C. Reber, S. N. Khanna, P. J. Roach, W. H. Woodward, A. W. Castleman, Jr., J. Am. Chem. Soc. 2007, 129, 16098.
    • Note added in proof (January 16, 2008): In a recent publication, odd/even electron alternations were reported for the gas-phase reactions of oxygen with aluminum-based cluster ions: A. C. Reber, S. N. Khanna, P. J. Roach, W. H. Woodward, A. W. Castleman, Jr., J. Am. Chem. Soc. 2007, 129, 16098.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.