密度泛函理论研究温度和取代基对4-亚芳基亚氨基-1,2,4-三唑-3(2H)-酮气相热分解的影响

采用密度泛函理论(DFT)方法, 在B3LYP/6-31＋＋G(d,p)水平上研究了4-亚芳基亚氨基-1,2,4-三唑-3(2H)-酮及其类似物的气相热分解反应. 从热力学性质、几何结构参数、自然电荷分布、温度效应等角度探讨不同取代基对标题物热分解反应的影响. 结果表明: R (R＝H, CH2CH2CN)取代基对反应影响很小; 而苯环上Y (Y＝MeO, Me, H, Cl和NO2)取代基对活化自由能(ΔG≠)、键长(ΔR≠)、键角(Δα≠)和自然电荷(Δq≠)变化的影响与Hammet常数(σ)呈现线性关系ΔP≠＝ρσ＋C (P＝G, R, α和q, r＞0.95). 给电子基团使得相应的活化自由能降低, 键长变短, 键角变大, 自然电荷增加; 吸电子反之.

Effects of Substituent and Temperature on the Gas-phase Pyrolysis of 4-Arylideneimino-1,2,4-triazol-3(2H)-ones: a DFT Investigation

The pyrolysis of 4-arylideneimino-l,2,4-triazol-3(2H)-one (ATO) and its analogues was investi-gated by the density functional theory method at the B3LYP/6-31 + +G(d,p) level of theory. The substituent and temperature effects on the title reaction have been discussed from the aspects of thermodynamic proper-ties, geometric parameters, and natural population analysis. The calculated results show that the substituent R has little effect on the reaction, while the changes caused by the substituents Y on the benzene ring (Y=MeO, Me, H, Cl, and NO_2) in the corresponding activation free energies (△G~≠), bond lengths (△R~≠), bond angles (△α~≠), and atomic charges (△q~≠) have linear correlations with Hammet constant (σ): △P~≠=pσ+C, (P=G, R, a and q, r>0.95). The electron-donating group decreases the activation free energies and bond lengths, but increases the bond angles and natural electric charges. By contraries, the electron-withdrawing group has the opposite effect.