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Femtosecond dynamics of dative bonding: Concepts of reversible and dissociative electron transfer reactions

Zhong, Dongping and Zewail, Ahmed H. (1999) Femtosecond dynamics of dative bonding: Concepts of reversible and dissociative electron transfer reactions. Proceedings of the National Academy of Sciences of the United States of America, 96 (6). pp. 2602-2607. ISSN 0027-8424.

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With fs time, speed, and angular resolution of the elementary steps in electron transfer reactions, we report direct observation of reversible and dissociative processes for dative bonding involving covalent and ionic characters. For bimolecular reactions of various donors and acceptors we find strong correlation between the structure and the dynamics. The dynamics from the transition state to final products involve two elementary processes, with different reaction times, speed, and angular distributions. For example, for the R2S·I2 (R = C2H5) system, it is shown that after charge separation, the reversible electron transfer occurs in less than 150 fs (fastest trajectory) and is followed by the rupture of the I---I bond with the release of the first I-atom in 510 fs. However, the second process of the remaining and trapped I-atom takes 1.15 ps with its speed (500 m/s) being much smaller than the first one (1,030 m/s). The S---I---I average angle is 130°. These findings, on this and the other systems reported here, elucidate the mechanism and address some concepts of nonconcertedness, caging, and restricted energy redistribution.

Item Type:Article
Additional Information:Contributed by Ahmed H. Zewail, January 13, 1999. We thank Dr. Thorsten M. Bernhardt for his help and discussion. This work is supported by a grant from the National Science Foundation, the Air Force Office of Scientific Research, and the Office of Naval Research.
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Deposited On:11 Jul 2005
Last Modified:14 Nov 2014 19:18

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