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Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*)

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2010
1134.pdf (795.8Kb)
Authors
George, Michael W.
Hall, Michael B.
Jina, Omar S.
Portius, Peter
Sun, Xue-Zhong
Towrie, Michael
Wu, Hong
Yang, Xinzheng
Zarić, Snežana D.
Article (Published version)
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Abstract
Fast time-resolved infrared spectroscopic measurements have allowed precise determination of the rates of activation of alkanes by Cp'Rh(CO) (Cp' = eta(5)-C5H5 or eta(5)-C5Me5). We have monitored the kinetics of C-H activation in solution at room temperature and determined how the change in rate of oxidative cleavage varies from methane to decane. The lifetime of CpRh(CO)(alkane) shows a nearly linear behavior with respect to the length of the alkane chain, whereas the related Cp*Rh(CO)(alkane) has clear oscillatory behavior upon changing the alkane. Coupled cluster and density functional theory calculations on these complexes, transition states, and intermediates provide the insight into the mechanism and barriers in order to develop a kinetic simulation of the experimental results. The observed behavior is a subtle interplay between the rates of activation and migration. Unexpectedly, the calculations predict that the most rapid process in these Cp'Rh (CO)(alkane) systems is the 1,3-...migration along the alkane chain. The linear behavior in the observed lifetime of CpRh(CO)(alkane) results from a mechanism in which the next most rapid process is the activation of primary C-H bonds (-CH3 groups), while the third key step in this system is 1,2-migration with a slightly slower rate. The oscillatory behavior in the lifetime of Cp*Rh(CO)(alkane) with respect to the alkane's chain length follows from subtle interplay between more rapid migrations and less rapid primary C-H activation, with respect to CpRh(CO)(alkane), especially when the CH3 group is near a gauche turn. This interplay results in the activation being controlled by the percentage of alkane conformers.

Keywords:
organometallic / photochemistry / computation / transition metal / sigma complex
Source:
Proceedings of the National Academy of Sciences of the United States, 2010, 107, 47, 20178-20183
Publisher:
  • Natl Acad Sciences, Washington
Funding / projects:
  • Proučavanje odnosa reaktivnosti, nekovalentnih interakcija i strukture molekula i modelovanje hemijskih sistema (RS-142037)
  • European Union, FP6-502440
  • Welch Foundation [A-0648]
  • National Science Foundation [CHE-0910552, CHE-0518074, CHE-0541587, DMS-0216275]
  • Wolfson Merit Award
  • Engineering and Physical Sciences Research Council

DOI: 10.1073/pnas.1001249107

ISSN: 0027-8424

PubMed: 21048088

WoS: 000284529000010

Scopus: 2-s2.0-78650585987
[ Google Scholar ]
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26
URI
https://cherry.chem.bg.ac.rs/handle/123456789/1136
Collections
  • Publikacije
Institution/Community
Hemijski fakultet
TY  - JOUR
AU  - George, Michael W.
AU  - Hall, Michael B.
AU  - Jina, Omar S.
AU  - Portius, Peter
AU  - Sun, Xue-Zhong
AU  - Towrie, Michael
AU  - Wu, Hong
AU  - Yang, Xinzheng
AU  - Zarić, Snežana D.
PY  - 2010
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/1136
AB  - Fast time-resolved infrared spectroscopic measurements have allowed precise determination of the rates of activation of alkanes by Cp'Rh(CO) (Cp' = eta(5)-C5H5 or eta(5)-C5Me5). We have monitored the kinetics of C-H activation in solution at room temperature and determined how the change in rate of oxidative cleavage varies from methane to decane. The lifetime of CpRh(CO)(alkane) shows a nearly linear behavior with respect to the length of the alkane chain, whereas the related Cp*Rh(CO)(alkane) has clear oscillatory behavior upon changing the alkane. Coupled cluster and density functional theory calculations on these complexes, transition states, and intermediates provide the insight into the mechanism and barriers in order to develop a kinetic simulation of the experimental results. The observed behavior is a subtle interplay between the rates of activation and migration. Unexpectedly, the calculations predict that the most rapid process in these Cp'Rh (CO)(alkane) systems is the 1,3-migration along the alkane chain. The linear behavior in the observed lifetime of CpRh(CO)(alkane) results from a mechanism in which the next most rapid process is the activation of primary C-H bonds (-CH3 groups), while the third key step in this system is 1,2-migration with a slightly slower rate. The oscillatory behavior in the lifetime of Cp*Rh(CO)(alkane) with respect to the alkane's chain length follows from subtle interplay between more rapid migrations and less rapid primary C-H activation, with respect to CpRh(CO)(alkane), especially when the CH3 group is near a gauche turn. This interplay results in the activation being controlled by the percentage of alkane conformers.
PB  - Natl Acad Sciences, Washington
T2  - Proceedings of the National Academy of Sciences of the United States
T1  - Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*)
VL  - 107
IS  - 47
SP  - 20178
EP  - 20183
DO  - 10.1073/pnas.1001249107
UR  - Kon_2136
ER  - 
@article{
author = "George, Michael W. and Hall, Michael B. and Jina, Omar S. and Portius, Peter and Sun, Xue-Zhong and Towrie, Michael and Wu, Hong and Yang, Xinzheng and Zarić, Snežana D.",
year = "2010",
abstract = "Fast time-resolved infrared spectroscopic measurements have allowed precise determination of the rates of activation of alkanes by Cp'Rh(CO) (Cp' = eta(5)-C5H5 or eta(5)-C5Me5). We have monitored the kinetics of C-H activation in solution at room temperature and determined how the change in rate of oxidative cleavage varies from methane to decane. The lifetime of CpRh(CO)(alkane) shows a nearly linear behavior with respect to the length of the alkane chain, whereas the related Cp*Rh(CO)(alkane) has clear oscillatory behavior upon changing the alkane. Coupled cluster and density functional theory calculations on these complexes, transition states, and intermediates provide the insight into the mechanism and barriers in order to develop a kinetic simulation of the experimental results. The observed behavior is a subtle interplay between the rates of activation and migration. Unexpectedly, the calculations predict that the most rapid process in these Cp'Rh (CO)(alkane) systems is the 1,3-migration along the alkane chain. The linear behavior in the observed lifetime of CpRh(CO)(alkane) results from a mechanism in which the next most rapid process is the activation of primary C-H bonds (-CH3 groups), while the third key step in this system is 1,2-migration with a slightly slower rate. The oscillatory behavior in the lifetime of Cp*Rh(CO)(alkane) with respect to the alkane's chain length follows from subtle interplay between more rapid migrations and less rapid primary C-H activation, with respect to CpRh(CO)(alkane), especially when the CH3 group is near a gauche turn. This interplay results in the activation being controlled by the percentage of alkane conformers.",
publisher = "Natl Acad Sciences, Washington",
journal = "Proceedings of the National Academy of Sciences of the United States",
title = "Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*)",
volume = "107",
number = "47",
pages = "20178-20183",
doi = "10.1073/pnas.1001249107",
url = "Kon_2136"
}
George, M. W., Hall, M. B., Jina, O. S., Portius, P., Sun, X., Towrie, M., Wu, H., Yang, X.,& Zarić, S. D.. (2010). Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*). in Proceedings of the National Academy of Sciences of the United States
Natl Acad Sciences, Washington., 107(47), 20178-20183.
https://doi.org/10.1073/pnas.1001249107
Kon_2136
George MW, Hall MB, Jina OS, Portius P, Sun X, Towrie M, Wu H, Yang X, Zarić SD. Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*). in Proceedings of the National Academy of Sciences of the United States. 2010;107(47):20178-20183.
doi:10.1073/pnas.1001249107
Kon_2136 .
George, Michael W., Hall, Michael B., Jina, Omar S., Portius, Peter, Sun, Xue-Zhong, Towrie, Michael, Wu, Hong, Yang, Xinzheng, Zarić, Snežana D., "Understanding the factors affecting the activation of alkane by Cp ' Rh(CO)(2) (Cp ' = Cp or Cp*)" in Proceedings of the National Academy of Sciences of the United States, 107, no. 47 (2010):20178-20183,
https://doi.org/10.1073/pnas.1001249107 .,
Kon_2136 .

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