State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, China.
J Comput Chem. 2013 Feb 15;34(5):372-8. doi: 10.1002/jcc.23144. Epub 2012 Oct 15.
The hydration of CO(2) in water solution was investigated by the cluster-continuum model calculations with n = 1-8 water molecules. For n = 1-4 water molecules, all the reactions follow a concerted pathway to the hydration product directly. For n = 5-8 water molecules, all the reactions follow a stepwise mechanism and a labile H(3)O(+) intermediate is involved in reaction. The surrounding water molecules from the bulk solvent play a key role in the proton relay process, which can stabilize the charged transition state and the H(3) O(+) intermediate in reaction. Furthermore, if the proton transfer from H(3)O(+) to the carbonyl oxygen occurs, the hydration pathway will be followed. If there is a proton transfer from H(3)O(+) to the outer water phase through the water bridge, the dissociation product of HCO(3)(-) will be formed. The predicted reaction energetics by current cluster-continuum model calculations shows good agreement with the experimental values. Present calculations strongly suggest the suitable cluster-continuum model including more explicit water molecules highly required for reasonable and unbiased description of the proton relay mechanism for proton transfer related reactions in water solution.
采用包含 1-8 个水分子的团簇-连续体模型计算研究了水溶液中 CO2 的水合作用。对于 n = 1-4 个水分子，所有反应都直接遵循协同途径生成水合产物。对于 n = 5-8 个水分子，所有反应都遵循逐步机制，涉及不稳定的 H(3)O(+)中间体。来自溶剂主体的周围水分子在质子传递过程中发挥关键作用，这可以稳定反应中的带电过渡态和 H(3)O(+)中间体。此外，如果 H(3)O(+)中的质子转移到羰基氧上，则会遵循水合途径。如果 H(3)O(+)中的质子通过水桥转移到外水相，则会形成 HCO(3)(-)的离解产物。当前的团簇-连续体模型计算预测的反应能学与实验值吻合良好。目前的计算强烈表明，需要合适的包含更多明确水分子的团簇-连续体模型，以便对质子传递相关反应在水溶液中的质子传递机制进行合理且无偏的描述。
