Femtochemistry of the iodine—arene charge-transfer complex

Lenderink, Egbert; Duppen, Koos; Wiersma, Douwe A.

doi:10.1016/0009-2614(93)80134-b

Cited by 37 publications

(71 citation statements)

References 50 publications

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“…78 We too see a rise within 100 fs and confirm the form of the transient reported by Lenderink et al 41 The extremely rapid birth of the D•I complex in solutions following the CT excitation is consistent with the ultrafast ionic-neutral surface switching mechanism we proposed for the gas-phase D•I 2 reactions.…”

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquisupporting

confidence: 89%

“…With ps resolution, Langhoff et al 40͑a͒ and Hilinski et al 40͑b͒ explored the dynamics of these complexes and showed the ultrafast nature of the reaction, though not resolved. Two fs studies of D•I 2 reactions in the liquid phase have been reported recently by the groups of Wiersma 41,42 and Sension. 43 Here, we will discuss these results and compare the initial dynamics ͑Ͻ1 ps͒ reported in solutions with our findings.…”

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 98%

“…With the advent of fs laser spectroscopy, the photochemistry of D•I 2 complexes has attracted new interest. Fs laser studies [41][42][43][44] have been reported recently and shown that the formation of D•I complexes is indeed extremely fast ͑25-500 fs͒ upon CT excitation of I 2 /D solutions. We will review and compare results of the liquid-phase fs studies with our gas-phase and cluster results in Sec.…”

Section: The Ct Systemmentioning

confidence: 99%

“…Using a CPM laser system, Lenderink et al 41 excited the complexes in I 2 /mesitylene and I 2 /toluene solutions at 310 nm and probed the photoproducts over the wavelength range from 400 to 700 nm. When they probed at 620 nm, they found that the transient absorption of the D•I complex rose within 25 fs.…”

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 99%

“…A transient absorption spectrum characteristic of molecular I 2 in solutions was also observed to appear on the same time scale, suggesting an impulsive fragmentation along the D-I 2 coordinate. Lenderink et al 41 concluded that the excited complex branches into two different channels through parallel exit routes in 25 fs. The major channel ͑75%͒ involves breaking up of the D•I 2 into its constitute molecules of D and I 2 .…”

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 99%

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Femtosecond real-time probing of reactions. XXI. Direct observation of transition-state dynamics and structure in charge-transfer reactions

Cheng

Zhong

Zewail

1996

The Journal of Chemical Physics

100

126

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Two-dimensional spectroscopy: Theory of nonstationary, time-dependent absorption and its application to femtosecond processes J. Chem. Phys. 91, 4485 (1989); 10.1063/1.456786 Femtosecond resolution ultrafast ion reaction time measurement a pulsed-laser field desorption time-of-flight spectroscopy AIP Conf. Proc. 146, 610 (1986) This paper in the series gives our full account of the preliminary results reported in a communication ͓Cheng, Zhong, and Zewail, J. Chem. Phys. 103, 5153 ͑1995͔͒ on real-time femtosecond ͑fs͒ studies of the transition state of charge-transfer ͑CT͒ reactions, generally described as harpooning reactions. Here, in a series of experimental studies in a molecular beam, and with the help of molecular dynamics, we elucidate the microscopic elementary dynamics and the structure of the transition states for the isolated, bimolecular reaction of benzenes ͑electron donor͒ with iodine ͑electron acceptor͒. The transition state is directly reached by fs excitation into the CT state of the complex Bz•I 2 , and the dynamics is followed by monitoring the product build up or the initial transition-state decay. We further employed the fs resolution in combination with the kinetic-energy resolved time-of-flight and recoil anisotropy techniques to separate different reaction pathways and to determine the impact geometry. Specifically, we have studied: ͑1͒ the temporal evolution of the transition state ͑ ‡ ͒ and of the final products ͑ ͒; ͑2͒ the product translational-energy distributions; ͑3͒ the recoil anisotropy ͑␤͒ in each channel; ͑4͒ the reaction time dependence on the total energy; ͑5͒ the dynamical and structural changes with varying CT energy ͑ionization potential-electron affinity-Coulomb energy͒. Such a change is made by replacing the electron donor from benzene to toluene, and to xylenes and trimethylbenzenes of different symmetries. We have also studied deutrobenzene as a donor. The reaction mechanism involves two exit channels. The first one ͑ionic͒ follows the ionic potential of the CT state. Following the harpooning ͑Bz ϩ•I 2 Ϫ ͒, the transition state•I͔* ‡ evolves on the adiabatic potential to produce Bz ϩ •I Ϫ and I products. The second channel ͑neutral͒ is due to the coupling of the transition state to neutral, locally excited, iodine repulsive states and, in this case, the products are Bz•IϩI. The latter process is an intermolecular electron transfer and occurs on an ultrafast time scale of 250 fs, resulting in a greater yield for the neutral channel. Molecular dynamics simulations support this dynamical picture and provide the time scales for trajectories in the transition-state region and in the product valley. The geometry of the transition state is determined from the anisotropy measurements and we found a nearly axial geometry with the iodine axis of recoil tilted 30°-35°away from the transition moment. These angular dependencies are related to the molecular structure and the electronic structure with highest occupied molecular orbit-lowest occupied molecular orbit descriptions. By...

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Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquisupporting

confidence: 89%

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 98%

Section: The Ct Systemmentioning

confidence: 99%

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 99%

Section: G Comparison With Liquid Phase and Cluster Studies 1 Liquimentioning

confidence: 99%

See 3 more Smart Citations

Femtosecond real-time probing of reactions. XXI. Direct observation of transition-state dynamics and structure in charge-transfer reactions

Cheng

Zhong

Zewail

1996

The Journal of Chemical Physics

100

126

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Ab initio molecular orbital and density functional study of the C6H6⋅I2 complex in the ground and excited electronic states

Mebel

Lin

1999

Int. J. Quant. Chem.

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Iodine-benzene charge-transfer complex: Potential energy surface and transition probabilities studied at several levels of theory

Grozema

Zijlstra

Swart

et al. 1999

Int. J. Quant. Chem.

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We present the results of detailed studies of the potential energy surfaces of the iodine–benzene charge‐transfer complex obtained from (fully counterpoise corrected) ab initio calculations at the second‐order Møller–Plesset (MP2) level and from (semi‐)classical calculations. The most stable conformations found were the above‐bond and the above‐carbon conformations. The axial conformation was found to be somewhat less stable. The remarkable difference in intermolecular distance for different orientations of the iodine is explained in terms of the polarization anisotropy. This feature makes the construction of an accurate classical force field rather difficult because of the marked dependence of the repulsion parameter—usually the radius—for iodine on both orientation and polarization of the iodine. Investigation of the oscillator strengths of different complex geometries shows that there are many conformations in which the charge‐transfer excitation can take place. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 709–723, 1999

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Femtochemistry of the iodine—arene charge-transfer complex

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Cited by 37 publications

References 50 publications

Femtosecond real-time probing of reactions. XXI. Direct observation of transition-state dynamics and structure in charge-transfer reactions

Femtosecond real-time probing of reactions. XXI. Direct observation of transition-state dynamics and structure in charge-transfer reactions

Ab initio molecular orbital and density functional study of the C6H6⋅I2 complex in the ground and excited electronic states

Iodine-benzene charge-transfer complex: Potential energy surface and transition probabilities studied at several levels of theory

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