NO3-+Cl2→ClONO2+Cl-反应势能面和势能阱

采用密度泛函理论B3LYP方法和6-311+G(d)基组, 计算构建离子-分子气相反应NO3-+Cl2→ClONO2+Cl-的三维势能面. 三维反应势能面证明该反应没有过渡态和势能垒, 但是存在一个深达-55.0 kJ/mol的势能阱(以氯气分子和硝酸根离子相隔无穷远为参量). 在势能阱底部, 有个化合物(O2NOClCl)- 称为势阱化合物, 依赖于势能阱而稳定存在. 理论红外光谱预测低温红外光谱能检测该势阱化合物. 低温条件下, 该反应由热力学控制, 反应产物是势阱化合物(O2NOClCl)-. 当温度升高, 该反应由动力学控制, 势阱化合物(O2NOClCl)-不稳定, 发生分解反应, 重新生成NO3-和Cl2. 研究结果可用来解释低温时ClONO2与Cl-气相反应不能产生Cl2的原因.

Potential Energy Surfaces and Potential Energy Well of Reaction NO3-+Cl2→ClONO2 + Cl-

The reaction potential surfaces(PESes) for the ion-molecule reaction of NO3-+Cl2 → ClONO2+Cl- were calculated at the B3LYP/6-311+G(d) level in the mode of three dimensions. Three original three-dimensional PESes prove that in the reaction there are no transition state and energy barrier, but there exists a potential energy well. The depth of the potential energy well is -55.0 kJ/mol(relative to NO3- and Cl2 completely be separated) calculated with CCSD(T)/6-311+G(d)// B3LYP/6-311+G(d). At the bottom of the well, there is a compound called Potential Well Compound(PWC), existing stably with the help of the well. The calculated theoretical infrared spectra predict that the PWC would be examined in low temperature infrared spectra. Our work shows that at low temperatures(~180 K) the reaction is dominated by its thermal dynamics. When the temperature going up, the PWC decomposes through reaction of(O2NOClCl)- → NO3-+Cl2, dominated by its chemical dynamics. Our study indicates that ClONO2 with Cl- cannot produce Cl2 at low temperatures in the gas-phase reaction.