摘要
对3-硝基-5-氨基-1,2,4-三唑(ANTA)的三种异构体,1H-ANTA(Ⅰ),2H-ANTA(Ⅱ)和4H-ANTA(Ⅲ),在ab initio-HF/3-21G和DFT-B3LYP/3-21G势能面计算的基础上,进行6-311G**几何参数全优化,MP2总能量和SCRF溶剂(四氢呋喃)效应计算.以振动分析和统计热力学为基础,作标题物热力学性质以及Ⅰ和Ⅱ之间的互变异构反应计算.求得分子几何,电子结构和300～1000 K范围的焓、熵和热容以及Ⅰ和Ⅱ互变异构平衡常数和速率常数.发现在三种异构体中在通常温度下以Ⅱ在气相下最稳定,Ⅰ在溶液中最稳定.低温下难以发生异构化反应,温度可提高Ⅰ与Ⅱ之间的互变速率,在800 K时两种异构体在气相中等量共存;大于800 K时Ⅰ更为稳定.
The fully optimized molecular geometries and electronic structures of isomers of 5 - amino - 3 nitrotriazole [1H - ANTA(I), 2H - ANTA( II) and 4H - ANTA( III)] are obtained by using ab initio method at HF/6 - 311G* * level and DFT method at B3LYP/6 - 311G* * level based on the potential energies surface scanning at the HF/3 - 21G and B3LYP/3 - 21G level, respectively. The accurate energies at MP2/6 - 311G* * //HF/6 - 311G* * level and solvation effects (in tetrahydrofuran) of three isomers have also been obtained. On the bases of the vibrational analysis and statistical thermodynamic theory, the thermodynamic parameters (enthalpies, entropies and heat capacities) for titled compounds, the equilibrium constants and rate constants of tautomerization of I reversible arrow II from 300 K to 1000 K, were calculated. The results show that II is the most stable among three titled compounds in gaseous state at ordinary temperature, and I is the most stable in liquid phase. The tautomerization reaction I reversible arrow II is difficult to occur at lower temperature. The tautomerism rate of 1H - ANTA and 2H - ANTA is up when the temperature increasing. II and I are equally coexisted in contents at 800 K. I is more stable than II at above 800 K.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2001年第6期895-900,共6页
Acta Chimica Sinica
基金
中国物理研究院自然科学基金
