Multilevel Quantum Mechanics Theories and Molecular Mechanics Calculations of the Cl- + CH3I Reaction in Water

作者：Liu, Peng; Li, Chen; Wang, Dunyou^*

来源：Journal of Physical Chemistry A, 2017, 121(41): 8012-8016.

DOI：10.1021/acs.jpca.7b08103

• DOUBLE-INVERSION MECHANISM
• DENSITY-FUNCTIONAL THEORY
• PHASE S(N)2 REACTIONS
• GAS-PHASE
• AQUEOUS-SOLUTION
• METHYL HALIDES
• ENERGIES
• HYDROCARBONS
• SIMULATIONS
• DYNAMICS

The Cl- + CH3I -> CH3Cl + I- reaction in water was studied using combined multilevel quantum mechanism theories and molecular mechanics with an explicit water solvent model. The study shows a significant influence of aqueous solution on the structures of the stationary points along the reaction pathway. A detailed, atomic-level evolution of the reaction mechanism shows a concerted one-bond-broken and one-bond-formed mechanism, as well as a synchronized charge-transfer process. The potentials of mean force calculated with the CCSD(T) and DFT treatments of the solute produce a free activation barrier at 24.5 and 19.0 kcal/mol, respectively, which agrees with the experimental one at 22.0 kcal/mol. The solvent effects have also been quantitatively analyzed: in total, the solvent effects raise the activation energy by 20.2 kcal/mol, which shows a significant impact on this reaction in water.

• 出版日期2017-10-19
• 单位山东师范大学