Secondary kinetic isotope effect in nucleophilic substitution: a quantum-mechanical approach

The Journal of Physical Chemistry. a
Carsten HennigStefan Schmatz

Abstract

Four-dimensional time-independent quantum scattering calculations have been carried out on the perdeuterated exothermic and complex-forming gas-phase S(N)2 reaction Cl- + CD3Br --> ClCD3 + Br- and the reverse process Br- + CD3Cl --> BrCD3 + Cl-, employing a fine energetic resolution to resolve all scattering resonances. The two totally symmetric modes of the methyl group, C-D symmetric stretch and umbrella bend, are explicitly taken into account. Converged state-selected reaction probabilities and product distributions have been calculated up to 2960 cm(-1) above the vibrational ground state of CD3Br, i.e., up to initial vibrational excitation of the second overtone of the umbrella bending vibration. The inverse secondary kinetic isotope effect found experimentally is nicely confirmed by the calculated state-selected reaction probabilities. One contribution to this originates from excitation of the high-frequency symmetric C-D stretching vibration, which increases the reaction probability as a function of translational energy more than the corresponding vibration in the undeuterated system. Although transition state theory (TST) suffices to explain this effect qualitatively, the dynamics of S(N)2 reactions is well-known to show...Continue Reading

References

Jun 8, 2004·Chemphyschem : a European Journal of Chemical Physics and Physical Chemistry·Stefan Schmatz

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Citations

Mar 29, 2011·ACS Applied Materials & Interfaces·Jinglei Xiang, Lawrence T Drzal
Dec 18, 2013·Journal of Mass Spectrometry : JMS·Chuanqing KangYuequan Sun
Jul 24, 2014·The Journal of Chemical Physics·U GasserA Fernandez-Nieves
Jan 1, 2009·The Journal of Physical Chemistry. a·Jiaxu ZhangWilliam L Hase
May 7, 2010·The Journal of Physical Chemistry. a·Jiaxu Zhang, William L Hase
Mar 23, 2011·Journal of the American Chemical Society·Lawrence M GoldmanBarry K Carpenter
Dec 28, 2019·Environmental Science & Technology·Frank KepplerStéphane Vuilleumier
Mar 4, 2020·The Journal of Physical Chemistry Letters·Luis RebollarMaureen H Tang

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