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In situ XAS study of the local structure and oxidation state evolution of palladium in a reduced graphene oxide supported Pd(II) carbene complex during an undirected C–H acetoxylation reaction

Yuan, Ning and Majeed, Maitham H. and Bajnóczi, Éva and Persson, Axel R. and Wallenberg, L. Reine and Inge, A. Ken and Heidenreich, Niclas and Stock, Norbert and Zou, Xiaodong and Wendt, Ola F. and Persson, Ingmar (2019). In situ XAS study of the local structure and oxidation state evolution of palladium in a reduced graphene oxide supported Pd(II) carbene complex during an undirected C–H acetoxylation reaction. Catalysis science & technology. 9, 2025-2031
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Abstract

In situ X-ray absorption spectroscopy (XAS) investigations have been performed to provide insights into the reaction mechanism of a palladium(II) catalyzed undirected C–H acetoxylation reaction in the presence of an oxidant. A Pd(II) N-heterocyclic carbene complex π-stacked onto reduced graphene oxide (rGO) was used as the catalyst. The Pd speciation during the catalytic process was examined by XAS, which revealed a possible mechanism over the course of the reaction. Pd(II) complexes in the as-synthesized catalyst first go through a gradual ligand substitution where chloride ions bound to Pd(II) are replaced by other ligands with a mean bond distance to Pd matching Pd–C/N/O. Parallel to this the mean oxidation state of Pd increases indicating the formation of Pd(IV) species. At a later stage, a fraction of the Pd complexes start to slowly transform into Pd nanoclusters. The mean average oxidation state of Pd decreases to the initial state at the end of the experiment which means that comparable amounts of Pd(0) and Pd(IV) are present. These observations from heterogeneous catalysis are in good agreement with its homogeneous analog and they support a Pd(II)–Pd(IV)–Pd(II) reaction mechanism.

Authors/Creators:Yuan, Ning and Majeed, Maitham H. and Bajnóczi, Éva and Persson, Axel R. and Wallenberg, L. Reine and Inge, A. Ken and Heidenreich, Niclas and Stock, Norbert and Zou, Xiaodong and Wendt, Ola F. and Persson, Ingmar
Title:In situ XAS study of the local structure and oxidation state evolution of palladium in a reduced graphene oxide supported Pd(II) carbene complex during an undirected C–H acetoxylation reaction
Year of publishing :2019
Volume:9
Page range:2025-2031
Number of Pages:7
Publisher:Royal Society of Chemistry
ISSN:2044-4753
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Inorganic Chemistry
Keywords:X-ray absorption spectroscopy (XAS), reaction mechanisms, palladium(II)
URN:NBN:urn:nbn:se:slu:epsilon-p-99638
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-99638
Additional ID:
Type of IDID
DOI10.1039/C8CY02430H
ID Code:16078
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Molecular Sciences
Deposited By: SLUpub Connector
Deposited On:23 Apr 2019 09:41
Metadata Last Modified:23 Apr 2019 10:02

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