NH_2与ClO自由基反应机理

Reaction mechanism of NH_2 with ClO

利用量子化学理论方法,研究了与大气臭氧层损耗密切相关的自由基反应NH2+ClO的微观机理。在密度泛函B3LYP/6-311+G(d,p)水平上优化得到反应路径上的反应物,过渡态,中间体和产物的几何构型,并通过振动频率分析对过渡态和中间体进行了确认。在高级电子相关组态相互作用QCISD(T)/6-311+G(d,p)水平上进行了单点能计算,得到了反应体系的势能面信息。结果表明,该反应经过缔合、H-转移和离解等过程,最终可以得到五种产物,分别为H2NO+Cl,H2NClO,HCl+HNO,H2+NO+Cl和NH+HClO。由于形成产物H2NO+Cl的活化势垒较低,因而是主要反应通道,而形成产物NH+HClO的通道从动力学上看是最不利的。

The mechanism for the radical reaction of NH2＋ClO crucial to stratospheric ozone depletion has been investigated theoretically. The geometries of reactions, transition states, intermediates and products have been optimized by B3LYP/6-311＋G（d,p） level and verified by frequency analysis. Single point energies have been calculated and the potential energy surface information has been obtained at the high-level electron-correlation QCISD（T）/6-311＋G（d,p） level. The results show that five products of H2NO＋Cl, H2NClO, HCl＋HNO, H2＋NO＋Cl and NH＋HClO can be obtained by association, H-shift and dissociation. The channel to yield H2NO＋Cl is the dominant one with lower energy barrier. The route to NH＋HClO is difficult kinetically.