Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study
Autori
Guan, JiaWriglesworth, Alisdair
Sun, Xue Zhong
Brothers, Edward N.
Zarić, Snežana D.
Evans, Meagan E.
Jones, William D.
Towrie, Michael
Hall, Michael B.
George, Michael W.
Članak u časopisu (Recenzirana verzija)
Metapodaci
Prikaz svih podataka o dokumentuApstrakt
Carbon-hydrogen bond activation of alkanes by Tp'Rh(CNR) (Tp' = Tp = trispyrazolylborate or Tp* = tris(3,5- dimethylpyrazolyl)borate) were followed by time-resolved infrared spectroscopy (TRIR) in the upsilon(CNR) and upsilon(B-H) spectral regions on Tp*Rh(CNCH2CMe3), and their reaction mechanisms were modeled by density functional theory (DFT) on TpRh(CNMe). The major intermediate species were: kappa(3)-eta(1)-alkane complex (1); kappa(2)-kappa(2)-alkane complex (2); and kappa(3)-alkyl hydride (3). Calculations predict that the barrier between 1 and 2 arises from a triplet-singlet crossing and intermediate 2 proceeds over the rate-determining C-H activation barrier to give the final product 3. The activation lifetimes measured for the Tp*Rh(CNR) and Tp*Rh(CO) fragments with n-heptane and four cycloalkanes (C5H10, C6H12, C7H14, and C8H16) increase with alkanes size and show a dramatic increase between C6H12 and C7H14. A similar step-like behavior was observed previously with CpRh(CO) a...nd Cp*Rh(CO) fragments and is attributed to the wider difference in C-H bonds that appear at C7H14. However, Tp'Rh(CNR) and Tp'Rh(CO) fragments have much longer absolute lifetimes compared to those of CpRh(CO) and Cp*Rh(CO) fragments, because the reduced electron density in dechelated kappa(2)-eta(2)-alkane Tp' complexes stabilizes the d(8) Rh(I) in a square-planar geometry and weakens the metal's ability for oxidative addition of the C-H bond. Further, the Tp'Rh(CNR) fragment has significantly slower rates of C-H activation in comparison to the Tp'Rh(CO) fragment for the larger cycloalkanes, because the steric bulk of the neopentyl isocyanide ligand hinders the rechelation in kappa(2)-Tp'Rh(CNR)(cycloalkane) species and results in the C-H activation without the assistance of the rechelation.
Izvor:
Journal of the American Chemical Society, 2018, 140, 5, 1842-1854Izdavač:
- Amer Chemical Soc, Washington
Finansiranje / projekti:
- Welch Foundation [A-0648]
- University of Nottingham Ningbo China
- Qatar National Research Fund (NPRP) [7-297-1-051]
- EPSRC [EP/I01974X]
Napomena:
- This is the peer-reviewed version of the following article: Guan, J.; Wriglesworth, A.; Sun, X. Z.; Brothers, E. N.; Zarić, S. D.; Evans, M. E.; Jones, W. D.; Towrie, M.; Hall, M. B.; George, M. W. Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp′Rh(CNR)(Carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study. Journal of the American Chemical Society 2018, 140 (5), 1842–1854. https://doi.org/10.1021/jacs.7b12152
- Supplementary material: http://cherry.chem.bg.ac.rs/handle/123456789/2942
DOI: 10.1021/jacs.7b12152
ISSN: 0002-7863
PubMed: 29290110
WoS: 000424851500038
Scopus: 2-s2.0-85042026603
Kolekcije
Institucija/grupa
Hemijski fakultet / Faculty of ChemistryTY - JOUR AU - Guan, Jia AU - Wriglesworth, Alisdair AU - Sun, Xue Zhong AU - Brothers, Edward N. AU - Zarić, Snežana D. AU - Evans, Meagan E. AU - Jones, William D. AU - Towrie, Michael AU - Hall, Michael B. AU - George, Michael W. PY - 2018 UR - https://cherry.chem.bg.ac.rs/handle/123456789/2893 AB - Carbon-hydrogen bond activation of alkanes by Tp'Rh(CNR) (Tp' = Tp = trispyrazolylborate or Tp* = tris(3,5- dimethylpyrazolyl)borate) were followed by time-resolved infrared spectroscopy (TRIR) in the upsilon(CNR) and upsilon(B-H) spectral regions on Tp*Rh(CNCH2CMe3), and their reaction mechanisms were modeled by density functional theory (DFT) on TpRh(CNMe). The major intermediate species were: kappa(3)-eta(1)-alkane complex (1); kappa(2)-kappa(2)-alkane complex (2); and kappa(3)-alkyl hydride (3). Calculations predict that the barrier between 1 and 2 arises from a triplet-singlet crossing and intermediate 2 proceeds over the rate-determining C-H activation barrier to give the final product 3. The activation lifetimes measured for the Tp*Rh(CNR) and Tp*Rh(CO) fragments with n-heptane and four cycloalkanes (C5H10, C6H12, C7H14, and C8H16) increase with alkanes size and show a dramatic increase between C6H12 and C7H14. A similar step-like behavior was observed previously with CpRh(CO) and Cp*Rh(CO) fragments and is attributed to the wider difference in C-H bonds that appear at C7H14. However, Tp'Rh(CNR) and Tp'Rh(CO) fragments have much longer absolute lifetimes compared to those of CpRh(CO) and Cp*Rh(CO) fragments, because the reduced electron density in dechelated kappa(2)-eta(2)-alkane Tp' complexes stabilizes the d(8) Rh(I) in a square-planar geometry and weakens the metal's ability for oxidative addition of the C-H bond. Further, the Tp'Rh(CNR) fragment has significantly slower rates of C-H activation in comparison to the Tp'Rh(CO) fragment for the larger cycloalkanes, because the steric bulk of the neopentyl isocyanide ligand hinders the rechelation in kappa(2)-Tp'Rh(CNR)(cycloalkane) species and results in the C-H activation without the assistance of the rechelation. PB - Amer Chemical Soc, Washington T2 - Journal of the American Chemical Society T1 - Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study VL - 140 IS - 5 SP - 1842 EP - 1854 DO - 10.1021/jacs.7b12152 ER -
@article{ author = "Guan, Jia and Wriglesworth, Alisdair and Sun, Xue Zhong and Brothers, Edward N. and Zarić, Snežana D. and Evans, Meagan E. and Jones, William D. and Towrie, Michael and Hall, Michael B. and George, Michael W.", year = "2018", abstract = "Carbon-hydrogen bond activation of alkanes by Tp'Rh(CNR) (Tp' = Tp = trispyrazolylborate or Tp* = tris(3,5- dimethylpyrazolyl)borate) were followed by time-resolved infrared spectroscopy (TRIR) in the upsilon(CNR) and upsilon(B-H) spectral regions on Tp*Rh(CNCH2CMe3), and their reaction mechanisms were modeled by density functional theory (DFT) on TpRh(CNMe). The major intermediate species were: kappa(3)-eta(1)-alkane complex (1); kappa(2)-kappa(2)-alkane complex (2); and kappa(3)-alkyl hydride (3). Calculations predict that the barrier between 1 and 2 arises from a triplet-singlet crossing and intermediate 2 proceeds over the rate-determining C-H activation barrier to give the final product 3. The activation lifetimes measured for the Tp*Rh(CNR) and Tp*Rh(CO) fragments with n-heptane and four cycloalkanes (C5H10, C6H12, C7H14, and C8H16) increase with alkanes size and show a dramatic increase between C6H12 and C7H14. A similar step-like behavior was observed previously with CpRh(CO) and Cp*Rh(CO) fragments and is attributed to the wider difference in C-H bonds that appear at C7H14. However, Tp'Rh(CNR) and Tp'Rh(CO) fragments have much longer absolute lifetimes compared to those of CpRh(CO) and Cp*Rh(CO) fragments, because the reduced electron density in dechelated kappa(2)-eta(2)-alkane Tp' complexes stabilizes the d(8) Rh(I) in a square-planar geometry and weakens the metal's ability for oxidative addition of the C-H bond. Further, the Tp'Rh(CNR) fragment has significantly slower rates of C-H activation in comparison to the Tp'Rh(CO) fragment for the larger cycloalkanes, because the steric bulk of the neopentyl isocyanide ligand hinders the rechelation in kappa(2)-Tp'Rh(CNR)(cycloalkane) species and results in the C-H activation without the assistance of the rechelation.", publisher = "Amer Chemical Soc, Washington", journal = "Journal of the American Chemical Society", title = "Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study", volume = "140", number = "5", pages = "1842-1854", doi = "10.1021/jacs.7b12152" }
Guan, J., Wriglesworth, A., Sun, X. Z., Brothers, E. N., Zarić, S. D., Evans, M. E., Jones, W. D., Towrie, M., Hall, M. B.,& George, M. W.. (2018). Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study. in Journal of the American Chemical Society Amer Chemical Soc, Washington., 140(5), 1842-1854. https://doi.org/10.1021/jacs.7b12152
Guan J, Wriglesworth A, Sun XZ, Brothers EN, Zarić SD, Evans ME, Jones WD, Towrie M, Hall MB, George MW. Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study. in Journal of the American Chemical Society. 2018;140(5):1842-1854. doi:10.1021/jacs.7b12152 .
Guan, Jia, Wriglesworth, Alisdair, Sun, Xue Zhong, Brothers, Edward N., Zarić, Snežana D., Evans, Meagan E., Jones, William D., Towrie, Michael, Hall, Michael B., George, Michael W., "Probing the Carbon-Hydrogen Activation of Alkanes Following Photolysis of Tp'Rh(CNR)(carbodiimide): A Computational and Time Resolved Infrared Spectroscopic Study" in Journal of the American Chemical Society, 140, no. 5 (2018):1842-1854, https://doi.org/10.1021/jacs.7b12152 . .