Mechanism Insights of Ethane C-H Bond Activations by Bare [Fe-III=O](+): Explicit Electronic Structure Analysis
(2012) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 116(5). p.1475-1485- Abstract
- Alkane C-H bond activation by various catalysts and enzymes has attracted considerable attention recently, but many issues are still unanswered. The conversion of ethane to ethanol and ethene by bare [Fe-III=O](+) has been explored using density functional theory and coupled-cluster method comprehensively. Two possible reaction mechanisms are available for the entire reaction, the direct H-abstraction mechanism and the concerted mechanism. First, in the direct H-abstraction mechanism, a direct H-abstraction is encountered in the initial step, going through a collinear transition state C center dot center dot center dot H center dot center dot center dot O-Fe and then leading to the generation of an intermediate Fe-OH bound to the alkyl... (More)
- Alkane C-H bond activation by various catalysts and enzymes has attracted considerable attention recently, but many issues are still unanswered. The conversion of ethane to ethanol and ethene by bare [Fe-III=O](+) has been explored using density functional theory and coupled-cluster method comprehensively. Two possible reaction mechanisms are available for the entire reaction, the direct H-abstraction mechanism and the concerted mechanism. First, in the direct H-abstraction mechanism, a direct H-abstraction is encountered in the initial step, going through a collinear transition state C center dot center dot center dot H center dot center dot center dot O-Fe and then leading to the generation of an intermediate Fe-OH bound to the alkyl radical weakly. The final product of the direct H-abstraction mechanism is ethanol, which is produced by the hydroxyl group back transfer to the carbon radical. Second, in the concerted reaction mechanism, the H-abstraction process is characterized via overcoming four/five-centered transition states (TSH)-T-6/4_c5 or (TSH)-T-4_c4. The second step of the concerted mechanism can lead to either product ethanol or ethene. Moreover, the major product ethene can be obtained through two different pathways, the one-step pathway and the stepwise pathway. It is the first report that the former pathway starting from (IM)-I-6/4_c to the product can be better described as a proton-coupled electron transfer (PCET). It plays an important role in the product ethene generation according to the CCSD(T) results. The spin-orbital coupling (SOC) calculations demonstrate that the title reaction should proceed via a two-state reactivity (TSR) pattern and that the spin-forbidden transition could slightly lower the rate-determining energy barrier height. This thorough theoretical study, especially the explicit electronic structure analysis, may provide important clues for understanding and studying the C-H bond activation promoted by iron-based artificial catalysts. (Less)
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https://lup.lub.lu.se/record/2409806
- author
- Sun, Xiao-Li ; Huang, Xu-Ri ; Li, Jilai LU ; Huo, Rui-Ping and Sun, Chia-Chung
- organization
- publishing date
- 2012
- type
- Contribution to journal
- publication status
- published
- subject
- in
- The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
- volume
- 116
- issue
- 5
- pages
- 1475 - 1485
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- wos:000299985100018
- scopus:84863161798
- pmid:22239679
- ISSN
- 1520-5215
- DOI
- 10.1021/jp2120302
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)
- id
- 8f8f4c6b-5647-4214-a83b-270b14b2b6d7 (old id 2409806)
- date added to LUP
- 2016-04-01 14:16:30
- date last changed
- 2023-04-06 20:11:56
@article{8f8f4c6b-5647-4214-a83b-270b14b2b6d7, abstract = {{Alkane C-H bond activation by various catalysts and enzymes has attracted considerable attention recently, but many issues are still unanswered. The conversion of ethane to ethanol and ethene by bare [Fe-III=O](+) has been explored using density functional theory and coupled-cluster method comprehensively. Two possible reaction mechanisms are available for the entire reaction, the direct H-abstraction mechanism and the concerted mechanism. First, in the direct H-abstraction mechanism, a direct H-abstraction is encountered in the initial step, going through a collinear transition state C center dot center dot center dot H center dot center dot center dot O-Fe and then leading to the generation of an intermediate Fe-OH bound to the alkyl radical weakly. The final product of the direct H-abstraction mechanism is ethanol, which is produced by the hydroxyl group back transfer to the carbon radical. Second, in the concerted reaction mechanism, the H-abstraction process is characterized via overcoming four/five-centered transition states (TSH)-T-6/4_c5 or (TSH)-T-4_c4. The second step of the concerted mechanism can lead to either product ethanol or ethene. Moreover, the major product ethene can be obtained through two different pathways, the one-step pathway and the stepwise pathway. It is the first report that the former pathway starting from (IM)-I-6/4_c to the product can be better described as a proton-coupled electron transfer (PCET). It plays an important role in the product ethene generation according to the CCSD(T) results. The spin-orbital coupling (SOC) calculations demonstrate that the title reaction should proceed via a two-state reactivity (TSR) pattern and that the spin-forbidden transition could slightly lower the rate-determining energy barrier height. This thorough theoretical study, especially the explicit electronic structure analysis, may provide important clues for understanding and studying the C-H bond activation promoted by iron-based artificial catalysts.}}, author = {{Sun, Xiao-Li and Huang, Xu-Ri and Li, Jilai and Huo, Rui-Ping and Sun, Chia-Chung}}, issn = {{1520-5215}}, language = {{eng}}, number = {{5}}, pages = {{1475--1485}}, publisher = {{The American Chemical Society (ACS)}}, series = {{The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory}}, title = {{Mechanism Insights of Ethane C-H Bond Activations by Bare [Fe-III=O](+): Explicit Electronic Structure Analysis}}, url = {{http://dx.doi.org/10.1021/jp2120302}}, doi = {{10.1021/jp2120302}}, volume = {{116}}, year = {{2012}}, }