Activation of Methane by Oligomeric (Al2O3)x+ (x=3,4,5): The Role of Oxygen‐Centered Radicals in Thermal Hydrogen‐Atom Abstraction

Feyel, Sandra; Döbler, Jens; Höckendorf, Robert F.; Beyer, Martin K.; Sauer, Joachim; Schwarz, Helmut

doi:10.1002/anie.200704791

Cited by 188 publications

(147 citation statements)

References 43 publications

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“…A crucial factor for the modeling of group 6 oxo surfaces is the proper choice of the molecular model size; therefore, the development of approaches that allows to experimentally unraveal cluster-size effects can contribute enormously to the understanding of heterogeneous catalytic processes. Our results support recent Schwarz´s group comclusions on vanadium and aluminium oxide ions, [51,52] which state that larger systems need to be considered to properly model heterogeneous surfaces. …”

Section: Discussionsupporting

confidence: 89%

Electrospray Ionization Based Methods for the Generation of Polynuclear Oxo- and Hydroxo Group 6 Anions in the Gas-Phase

2008

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Electrospray ionization (ESI) of the Lindqvist (n-Bu-(n = 1-6) species can be readily generated in the gas-phase upon varying the solvent composition as well as the ionisation conditions (typically the U c cone voltage). Complementary tandem mass experiments (collision induced dissociation and ion-molecule reactions) are also used aimed to investigate the consecutive dissociation of these species and their intrinsic gas-phase reactivity towards methanol. Special emphasis is paid to some of the key factors of these group 6 anions related to the gas-phase activation of methanol, such as molecular composition, open vs closed shell electronic nature and cluster size.

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Section: Discussionsupporting

confidence: 89%

Electrospray Ionization Based Methods for the Generation of Polynuclear Oxo- and Hydroxo Group 6 Anions in the Gas-Phase

2008

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“…AlO 3 − has a planar, triangular structure with a peroxo group, and AlO 4 − is a closed-shell D 2d symmetric molecule with two overstretched peroxo groups. The binuclear species Al 2 O [3][4][5][6] − are all open-shell doublets and oxygencentered radicals. The common motif is a four-membered Al-(O 2 )-Al ring, with one or two terminal oxo groups (n = 3, 4), or with oxo/superoxo (n = 5) and peroxo/superoxo groups (n = 6).…”

Section: Discussionmentioning

confidence: 99%

“…Experiments on these model systems thus provide insight into structure-reactivity correlations as well as the transition from molecular to condensed phase properties. [2][3][4] Small aluminum oxide cluster cations 5,6 and anions 7 containing oxygen-centered radicals have raised interest recently as models for understanding water chemisorption and C-H bond activation. There is also an astrochemical interest in the role that small aluminum oxide clusters play in the formation of circumstellar corundum (Al 2 O 3 ) grains.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, anharmonic effects, like Fermi resonances, prove to be important for explaining the experimental IR spectra. Previous mass spectrometric investigations on gas phase aluminum oxide cluster ions have focused on their reactivity towards water, 6,9 carbon monoxide, 10 ammonia, 11 methane, 5,6 and larger alkanes. 7 The smaller anions show a variety of reactions, but react more selectively than the corresponding cations.…”

Section: Introductionmentioning

confidence: 99%

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Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

Song

Fagiani

Gewinner

et al. 2016

The Journal of Chemical Physics

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We use cryogenic ion trap vibrational spectroscopy in combination with quantum chemical calculations to study the structure of mono-and dialuminum oxide anions. The infrared photodissociation spectra of D 2 -tagged AlO 1-4 − and Al 2 O 3-6 − are measured in the region from 400 to 1200 cm −1 . Structures are assigned based on a comparison to simulated harmonic and anharmonic IR spectra derived from electronic structure calculations. The monoaluminum anions contain an even number of electrons and exhibit an electronic closed-shell ground state. The Al 2 O 3-6 − anions are oxygen-centered radicals. As a result of a delicate balance between localization and delocalization of the unpaired electron, only the BHLYP functional is able to qualitatively describe the observed IR spectra of all species with the exception of AlO 3 − . Terminal Al-O stretching modes are found between 1140 and 960 cm −1 . Superoxo and peroxo stretching modes are found at higher (1120-1010 cm −1 ) and lower energies (850-570 cm −1 ), respectively. Four modes in-between 910 and 530 cm −1 represent the IR fingerprint of the common structural motif of dialuminum oxide anions, an asymmetric four-member Al-(O) 2 -Al ring. Published by AIP Publishing. [http://dx

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“…It shares the O Á-radical site with the polynuclear (Al 2 O 3 ) 4 Á? radical cation which has also been found to abstract hydrogen from methane and to yield methyl radicals [14]. Such O Á-radical sites, neighbored to Li ?…”

Section: Introductionmentioning

confidence: 99%

Models in Catalysis

2014

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The paper discusses the hierarchy of model studies with increasing complexity towards an understanding of industrial catalysts under reaction conditions. We use three case studies to document the progress in systems complexity as well as the development of instruments that allow us to approach the study of acting catalysts: magnesium oxide clusters in the gas phase, gold nanoparticles on metal oxide surfaces, and palladium nanoparticles compared to crystal surfaces. While the examples are from the field of heterogeneous catalysis, we discuss the relation to homogeneous and enzymatic catalysis.

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Activation of Methane by Oligomeric (Al₂O₃)_x⁺ (x=3,4,5): The Role of Oxygen‐Centered Radicals in Thermal Hydrogen‐Atom Abstraction

Cited by 188 publications

References 43 publications

Electrospray Ionization Based Methods for the Generation of Polynuclear Oxo- and Hydroxo Group 6 Anions in the Gas-Phase

Electrospray Ionization Based Methods for the Generation of Polynuclear Oxo- and Hydroxo Group 6 Anions in the Gas-Phase

Gas phase structures and charge localization in small aluminum oxide anions: Infrared photodissociation spectroscopy and electronic structure calculations

Models in Catalysis

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