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

doi: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

David C. Grills, Kuo Wei Huang, James T. Muckerman, Etsuko Fujita^*

^*Corresponding author for this work

Research output: Contribution to journal › Review article › peer-review

15 Scopus citations

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, K_N2 = (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.

Original language	English (US)
Pages (from-to)	1681-1695
Number of pages	15
Journal	Coordination Chemistry Reviews
Volume	250
Issue number	13-14
DOIs	https://doi.org/10.1016/j.ccr.2006.01.002
State	Published - Jul 2006
Externally published	Yes

Bibliographical note

Funding Information:
We thank Prof. M.W. George for the provision of unpublished data. This work was performed at Brookhaven National Laboratory, funded under contract DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. K.-W.H. acknowledges a Gertrude and Maurice Goldhaber Distinguished Fellowship.

Keywords

Binding rates
Dinitrogen complex
Flash photolysis
Nitrogen fixation
Time-resolved Infrared

ASJC Scopus subject areas

General Chemistry
Materials Chemistry
Inorganic Chemistry
Physical and Theoretical Chemistry

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10.1016/j.ccr.2006.01.002

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@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 Huang, {Kuo Wei} and Muckerman, {James T.} and Etsuko Fujita",

note = "Funding Information: We thank Prof. M.W. George for the provision of unpublished data. This work was performed at Brookhaven National Laboratory, funded under contract DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. K.-W.H. acknowledges a Gertrude and Maurice Goldhaber Distinguished Fellowship. ",

year = "2006",

month = jul,

doi = "10.1016/j.ccr.2006.01.002",

language = "English (US)",

volume = "250",

pages = "1681--1695",

journal = "Coordination Chemistry Reviews",

issn = "0010-8545",

publisher = "Elsevier B.V.",

number = "13-14",

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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

N1 - Funding Information: We thank Prof. M.W. George for the provision of unpublished data. This work was performed at Brookhaven National Laboratory, funded under contract DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. K.-W.H. acknowledges a Gertrude and Maurice Goldhaber Distinguished Fellowship.

PY - 2006/7

Y1 - 2006/7

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 - Nitrogen fixation

KW - Time-resolved Infrared

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U2 - 10.1016/j.ccr.2006.01.002

DO - 10.1016/j.ccr.2006.01.002

M3 - Review article

AN - SCOPUS:33745171773

SN - 0010-8545

VL - 250

SP - 1681

EP - 1695

JO - Coordination Chemistry Reviews

JF - Coordination Chemistry Reviews

IS - 13-14

ER -

Kinetic studies of the photoinduced formation of transition metal-dinitrogen complexes using time-resolved infrared and UV-vis spectroscopy

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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