Direct Identification of Acetaldehyde Formation and Characterization of the Active Site in the [VPO4].+/C2H4 Couple by Gas‐Phase Vibrational Spectroscopy

The gas‐phase reaction of the heteronuclear oxide cluster [VPO4].+ with C2H4 is studied under multiple collision conditions at 150 K using cryogenic ion‐trap vibrational spectroscopy combined with electronic structure calculations. The exclusive formation of acetaldehyde is directly identified spect...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2019-12, Vol.58 (52), p.18868-18872
Main Authors: Li, Ya‐Ke, Debnath, Sreekanta, Schlangen, Maria, Schöllkopf, Wieland, Asmis, Knut R., Schwarz, Helmut
Format: Article
Language:English
Subjects:
Acetaldehyde
active site
Communication
Communications
Computer applications
cryogenic ion trap
Electronic structure
heteronuclear oxide clusters
infrared photodissociation spectroscopy
olefin oxidation
Reaction mechanisms
Spectroscopy
Spectrum analysis
Structural analysis
Vanadium
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Summary:The gas‐phase reaction of the heteronuclear oxide cluster [VPO4].+ with C2H4 is studied under multiple collision conditions at 150 K using cryogenic ion‐trap vibrational spectroscopy combined with electronic structure calculations. The exclusive formation of acetaldehyde is directly identified spectroscopically and discussed in the context of the underlying reaction mechanism. In line with computational predictions it is the terminal P=O and not the V=O unit that provides the oxygen atom in the barrier‐free thermal C2H4→CH3CHO conversion. Interestingly, in the course of the reaction, the emerging CH3CHO product undergoes a rather complex intramolecular migration, coordinating eventually to the vanadium center prior to its liberation. Moreover, the spectroscopic structural characterization of neutral C2H4O deserves special mentioning as in most, if not all, ion/molecule reactions, the neutral product is usually only indirectly identified. Caught in the act: The gas‐phase reaction of the heteronuclear oxide cluster [VPO4].+ with C2H4 was studied by infrared photodissociation spectroscopy, which directly identified the formation of acetaldehyde and revealed the terminal P=O moiety as the active site of [VPO4].+ in the oxygen atom transfer (OAT) reaction with ethylene, in line with theoretical predictions.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201911040