全氟温室气体 NF3与 H 自由基脱氟反应机理

摘要

The reaction mechanisms of NF 3 and H were studied in detail by using the density functional theory ( DFT) .The ge-ometries of reactants, transition states, intermediates and products were optimized at the B 3PW91/6-311++G(d,p) level of theory. The connections of the transition states with reactants and products were calculated by the intrinsic reaction coordinate ( IRC) meth-od at the same level.High accurate energy information was provided by the QCISD (T)/6-311++G(d,p)//B3PW91/6-311++G (d,p)+ZPE method.The results show that the reaction of NF 3 and H has two types of mechanisms , i.e.direct abstraction and addi-tion-elimination.The reaction barriers for the transition states of TS1, TS2 and TS3 are 52.7, 70.4 and 76.5 kJψmol-1, respectively. All the reactions are exothermic and the energy of products NF 2+HF is -337.9 kJψmol-1 .%用密度泛函B3PW91／6－311＋＋G（ d，p）方法研究了全氟温室气体NF3与H自由的脱氟反应机理，对反应势能面上各驻点的几何构型进行了全参数优化，并且对所有过渡态进行了确认。为获得更精确的能量，用较高水平QCISD（T）／6－311＋＋G（d，p）／／B3PW91／6－311＋＋G（d，p）＋ZPE进行了单点能校正。结果表明，NF3可经过两种反应机理脱去一个F原子：即直接抽提机理和加成－消去机理，反应的势垒分别为52．7、70．4和76．5 kJ鬃mol－1，直接抽提反应是标题反应的主反应通道。所有反应均为放热反应，裂解产物NF2＋HF相对于反应物的能量为－337．9 kJ鬃mol－1。