F_2+2HCl→2HF+Cl_2反应机理的密度泛函理论研究

A Study on the Mechanism of the Reaction F_2 + 2HCl→2HF + Cl_2 Using Density Functional Theory

用密度泛函理论(DFT)B3LYP方法,在6-311G^(**)基组下,计算研究了反应F_2+2HCl→2HF+Cl_2的机理.求得各可能反应途径的系列过渡态,并通过振动分析和内禀反应坐标(IRC)分析加以证实.比较反应能垒(理论计算活化能)发现,标题反应若以分子与分子作用机理进行,则需克服的最大能垒为150.63kJ·mol^(-1)若以F_2分子先裂解为F原子再反应的机理进行,则需越过能垒154.82kJ·mol^(-1)求得反应F+HCl→HF+Cl的线形和三角形两种过渡态,以三角形较稳定;求得反应HCl+Cl→H+Cl_2的两种过渡态,以线形较稳定.

The mechanism of the reaction F2 + 2HCl →2HF + Cl2 has been investigated using density functional theory(DFT) at the B3LYP/6 - 311G* * level. The transition states for all the possible reaction paths are obtained and verified by vibrational analyses and IRC calculations. By comparing the calculated barriers, it is found that the largest barrier for the mechanism of molecule - molecule interaction is 150.63kJ·mol-1. The corresponding barrier for the mechanism in which F2 is cleavaged first before the resulting F atoms react with the other reactants is 154.82kJ. For the reaction F + HCl→ HF + Cl, two types of transition states are located. One is linear, the another is triangle and it is more stable. Between two transition states for the reaction HCl + CH→H + Cl2, the linear one is more stable.