Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy
David C. Grills, Kuo-Wei Huang, James T. Muckerman, Etsuko Fujita*
Previous kinetic studies of photoinitiated transition metal-dinitrogen bond forming reactions are reviewed, with an emphasis on room temperature reactivity, and in particular, the techniques of time-resolved infrared (TRIR) spectroscopy and UV-vis flash photolysis. Our recent results on the reactivity of the formally 16-electron, but agostically stabilized, complex, mer,trans-W(CO)3(PCy3)2 (W) (Cy = cyclohexyl) toward N2 in toluene and n-hexane solution are then discussed. Laser flash photolysis of a toluene solution of W-N2 in the presence of excess N2 resulted in the photoejection of N2. The back reaction of W with N2 was followed by monitoring the decay of the transient absorption of W at 600 nm. The second-order rate constant for the reaction of N2 with W in toluene to generate W-N2 was found to be (3.0 ± 0.2) × 105 M-1 s-1. The rate of the reverse reaction was found to be 100 ± 10 s-1, allowing an estimation of the equilibrium constant, KN2 = (3.0 ± 0.5) × 103 M- 1. Time-resolved step-scan FTIR (s2-FTIR) spectroscopy was also used to spectroscopically characterize the W intermediate and monitor its back-reaction with N2 in n-hexane solution. The rate of formation of W-N2 measured by s2-FTIR agreed well with that measured by flash photolysis. Finally, density functional theory (DFT) calculations have been performed on the model complexes, mer,trans-W(CO)3(PH3)2(L) (L = none and N2) in order to understand the observed IR and UV-vis spectra of W and W-N2 and to determine the nature of the frontier molecular orbitals of W and W-N2, allowing their lowest energy excited states to be assigned.
Coordination Chemistry Reviews
https://doi.org/10.1016/j.ccr.2006.01.002
Binding rates
Dinitrogen complex
Flash photolysis
Time-resolved Infrared
10.1016/j.ccr.2006.01.002
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Photolysis Chemical Compounds 100%
Metal complexes Chemical Compounds 93%
Transition metals Chemical Compounds 84%
Toluene Chemical Compounds 74%
Spectroscopy Chemical Compounds 63%
n-hexane Chemical Compounds 54%
Infrared radiation Chemical Compounds 49%
Carbon Monoxide Chemical Compounds 39%
Grills, D. C., Huang, K-W., Muckerman, J. T., & Fujita, E. (2006). Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy. Coordination Chemistry Reviews, 250(13-14), 1681-1695. https://doi.org/10.1016/j.ccr.2006.01.002
Grills, David C. ; Huang, Kuo-Wei ; Muckerman, James T. ; Fujita, Etsuko. / Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy. In: Coordination Chemistry Reviews. 2006 ; Vol. 250, No. 13-14. pp. 1681-1695.
@article{d0891e864d9a4ad69b287b8f94ead355,
title = "Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy",
abstract = "Previous kinetic studies of photoinitiated transition metal-dinitrogen bond forming reactions are reviewed, with an emphasis on room temperature reactivity, and in particular, the techniques of time-resolved infrared (TRIR) spectroscopy and UV-vis flash photolysis. Our recent results on the reactivity of the formally 16-electron, but agostically stabilized, complex, mer,trans-W(CO)3(PCy3)2 (W) (Cy = cyclohexyl) toward N2 in toluene and n-hexane solution are then discussed. Laser flash photolysis of a toluene solution of W-N2 in the presence of excess N2 resulted in the photoejection of N2. The back reaction of W with N2 was followed by monitoring the decay of the transient absorption of W at 600 nm. The second-order rate constant for the reaction of N2 with W in toluene to generate W-N2 was found to be (3.0 ± 0.2) × 105 M-1 s-1. The rate of the reverse reaction was found to be 100 ± 10 s-1, allowing an estimation of the equilibrium constant, KN2 = (3.0 ± 0.5) × 103 M- 1. Time-resolved step-scan FTIR (s2-FTIR) spectroscopy was also used to spectroscopically characterize the W intermediate and monitor its back-reaction with N2 in n-hexane solution. The rate of formation of W-N2 measured by s2-FTIR agreed well with that measured by flash photolysis. Finally, density functional theory (DFT) calculations have been performed on the model complexes, mer,trans-W(CO)3(PH3)2(L) (L = none and N2) in order to understand the observed IR and UV-vis spectra of W and W-N2 and to determine the nature of the frontier molecular orbitals of W and W-N2, allowing their lowest energy excited states to be assigned.",
keywords = "Binding rates, Dinitrogen complex, Flash photolysis, Nitrogen fixation, Time-resolved Infrared",
author = "Grills, {David C.} and Kuo-Wei Huang and Muckerman, {James T.} and Etsuko Fujita",
doi = "10.1016/j.ccr.2006.01.002",
journal = "Coordination Chemistry Reviews",
Grills, DC, Huang, K-W, Muckerman, JT & Fujita, E 2006, 'Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy', Coordination Chemistry Reviews, vol. 250, no. 13-14, pp. 1681-1695. https://doi.org/10.1016/j.ccr.2006.01.002
Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy. / Grills, David C.; Huang, Kuo-Wei; Muckerman, James T.; Fujita, Etsuko.
In: Coordination Chemistry Reviews, Vol. 250, No. 13-14, 01.07.2006, p. 1681-1695.
T1 - Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy
AU - Grills, David C.
AU - Huang, Kuo-Wei
AU - Muckerman, James T.
AU - Fujita, Etsuko
N2 - Previous kinetic studies of photoinitiated transition metal-dinitrogen bond forming reactions are reviewed, with an emphasis on room temperature reactivity, and in particular, the techniques of time-resolved infrared (TRIR) spectroscopy and UV-vis flash photolysis. Our recent results on the reactivity of the formally 16-electron, but agostically stabilized, complex, mer,trans-W(CO)3(PCy3)2 (W) (Cy = cyclohexyl) toward N2 in toluene and n-hexane solution are then discussed. Laser flash photolysis of a toluene solution of W-N2 in the presence of excess N2 resulted in the photoejection of N2. The back reaction of W with N2 was followed by monitoring the decay of the transient absorption of W at 600 nm. The second-order rate constant for the reaction of N2 with W in toluene to generate W-N2 was found to be (3.0 ± 0.2) × 105 M-1 s-1. The rate of the reverse reaction was found to be 100 ± 10 s-1, allowing an estimation of the equilibrium constant, KN2 = (3.0 ± 0.5) × 103 M- 1. Time-resolved step-scan FTIR (s2-FTIR) spectroscopy was also used to spectroscopically characterize the W intermediate and monitor its back-reaction with N2 in n-hexane solution. The rate of formation of W-N2 measured by s2-FTIR agreed well with that measured by flash photolysis. Finally, density functional theory (DFT) calculations have been performed on the model complexes, mer,trans-W(CO)3(PH3)2(L) (L = none and N2) in order to understand the observed IR and UV-vis spectra of W and W-N2 and to determine the nature of the frontier molecular orbitals of W and W-N2, allowing their lowest energy excited states to be assigned.
AB - Previous kinetic studies of photoinitiated transition metal-dinitrogen bond forming reactions are reviewed, with an emphasis on room temperature reactivity, and in particular, the techniques of time-resolved infrared (TRIR) spectroscopy and UV-vis flash photolysis. Our recent results on the reactivity of the formally 16-electron, but agostically stabilized, complex, mer,trans-W(CO)3(PCy3)2 (W) (Cy = cyclohexyl) toward N2 in toluene and n-hexane solution are then discussed. Laser flash photolysis of a toluene solution of W-N2 in the presence of excess N2 resulted in the photoejection of N2. The back reaction of W with N2 was followed by monitoring the decay of the transient absorption of W at 600 nm. The second-order rate constant for the reaction of N2 with W in toluene to generate W-N2 was found to be (3.0 ± 0.2) × 105 M-1 s-1. The rate of the reverse reaction was found to be 100 ± 10 s-1, allowing an estimation of the equilibrium constant, KN2 = (3.0 ± 0.5) × 103 M- 1. Time-resolved step-scan FTIR (s2-FTIR) spectroscopy was also used to spectroscopically characterize the W intermediate and monitor its back-reaction with N2 in n-hexane solution. The rate of formation of W-N2 measured by s2-FTIR agreed well with that measured by flash photolysis. Finally, density functional theory (DFT) calculations have been performed on the model complexes, mer,trans-W(CO)3(PH3)2(L) (L = none and N2) in order to understand the observed IR and UV-vis spectra of W and W-N2 and to determine the nature of the frontier molecular orbitals of W and W-N2, allowing their lowest energy excited states to be assigned.
KW - Binding rates
KW - Dinitrogen complex
KW - Flash photolysis
KW - Time-resolved Infrared
U2 - 10.1016/j.ccr.2006.01.002
DO - 10.1016/j.ccr.2006.01.002
JO - Coordination Chemistry Reviews
JF - Coordination Chemistry Reviews
Grills DC, Huang K-W, Muckerman JT, Fujita E. Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy. Coordination Chemistry Reviews. 2006 Jul 1;250(13-14):1681-1695. https://doi.org/10.1016/j.ccr.2006.01.002