Annapureddy Harsha V R, Dang Liem X
Physical Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 93352, United States.
J Phys Chem B. 2014 Jul 17;118(28):7886-91. doi: 10.1021/jp500402j. Epub 2014 Mar 24.
Molecular dynamics simulations were performed to systematically study the water-exchange mechanism around aqueous chloride, bromide, and iodide ions. Transition state theory, Grote-Hynes theory, and the reactive flux method were employed to compute water exchange rates. We computed the pressure dependence of rate constants and the corresponding activation volumes to investigate the mechanism of the solvent exchange event. The activation volumes obtained using the transition state theory rate constants are negative for all the three anions, thus indicating an associative mechanism. Contrary to the transition state theory results, activation volumes obtained using rate constants from Grote-Hynes theory and the reactive flux method are positive, thus indicating a dissociative mechanism.
进行了分子动力学模拟，以系统地研究氯离子、溴离子和碘离子周围的水交换机制。采用过渡态理论、格罗特-海因斯理论和反应通量方法来计算水交换速率。我们计算了速率常数的压力依赖性和相应的活化体积，以研究溶剂交换过程的机制。使用过渡态理论速率常数获得的活化体积对于所有三种阴离子都是负的，因此表明是缔合机制。与过渡态理论结果相反，使用格罗特-海因斯理论和反应通量方法的速率常数获得的活化体积是正的，因此表明是解离机制。
