HNCO与NH_3,H_2O和HF反应机理的理论化学研究

The Theoretical Study on the Reaction Mechanism of HNCO with NH_3,H_2O and HF

使用Gaussian03软件,DFT密度泛函方法B3LYP和6-31++G(d,p)基组,研究和比较了异氰酸(HNCO)与NH3,H2O和HF分子的IRC反应路径,通过振动分析确认了过渡态的结构.计算结果表明3个反应都是放热反应,反应中1个σ键和1个π键断裂,2个新的σ键生成;过渡态最显著的特征是H原子的转移;过渡态是四元环结构,由于NH3,H2O和HF分子中N,O和F原子电负性的不同,四元环形状有比较明显的差异.

<Abstrcat> The additional reactions of HNCO with NH_3, H_2O and HF have been investigated with Gaussian 03 at B3LYP/6-31++G(d, p) level. Vibration analysis was carried out to confirm its identity as a transition structure. The intrinsic reaction coordinate (IRC) was performed. The calculated results showed that the three reactions were exothermal reaction in which one σ bond and one π bond broke, and the other two new σ bonds formed. The characteristic of reaction in transition state was the transfer of H atom and the four-membered ring formed. Due to the different in electron-withdrawing ability of the atom N, O and F in NH_3, H_2O and HF molecules, the geometry of the four-membered ring appeared obviously different.