A multilayered representation,quantum mechanical and molecular mechanics study of the CH3F + OH− reaction in water |
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| Authors: | Jie Chen Yulong Xu Dunyou Wang |
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| Affiliation: | 1. College of Physics and Electronics, Shandong Normal University, Jinan, China;2. Department of Physics, School of Science, Qilu University of Technology, Jinan |
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| Abstract: | The bimolecular nucleophilic substitution (SN2) reaction of CH3F + OH? in aqueous solution was investigated using a combined quantum mechanical and molecular mechanics approach. Reactant complex, transition state, and product complex along the reaction pathway were analyzed in water. The potentials of mean force were calculated using a multilayered representation with the DFT and CCSD(T) level of theory for the reactive region. The obtained free energy activation barrier for this reaction at the CCSD(T)/MM representation is 18.3 kcal/mol which agrees well with the experimental value at ～21.6 kcal/mol. Both the solvation effect and solute polarization effect play key roles on raising the activation barrier height in aqueous solution, with the former raising the barrier height by 3.1 kcal/mol, the latter 1.5 kcal/mol. © 2013 Wiley Periodicals, Inc. |
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| Keywords: | quantum mechanical/molecular mechanics SN2 reaction aqueous solution potential mean force barrier height reaction pathway nucleophile |
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