中文摘要：

用密度泛函B3LYP／6-311＋＋G^＊＊方法，对气相和水相中的1，2，3，-三唑及5-卤（-F、Cl和-Br）代1，2，3，-三唑互变异构体进行了几何构型全自由度优化，获得了它们在气相和水相中的几何结构和电子结构。计算结果显示，在气相和水相中1，2，3-三唑和5-卤代1，2，3-三唑的N2-H型要比对应的N1-H型和N3-H型稳定。讨论了不同的取代基团和溶剂化效应对互变异构体的几何结构、能量和电荷分布以及互变异构反应活化能的影响带。并进一步研究了N1-H、N2-H和N3-H型三唑之间的互变异构机理：（a）分子内质子转移；（b）水助质子转移。计算结果表明，途径（b）所需要的活化能较小，为120．06KJ／mol，途径（a）为204．12KJ／mol。

英文摘要：

Molecular structures of 1,2,3 - triazoles and C5 - halogeno - triazole tautomers were calculated by the B3LYP method at the 6 - 311 ＋ ＋ G^＊＊ level both in the gaseous and aqueous phases with full geometry optimization. The geometrical and electronic structure of the tautomers of 1,2,3 -triazoles and C5 -halogeno- triazole and their transition states were obtained. The results of the calculation indicated that N2 - H tautomers form is more stable than that of N1 - H and N3 - H forms. The influence of the different 5 - halogeno and solvent effect on the geometrical structure,energy,charge,and activated energy were discussed. The reaction mechanism of tautomers of 1,2,3 - triazoles and CS - halogeno - triazole were also studied. There are two reaction pathways： （a） intramolecular proton transfer; （b） water - assisted intermolecular transfer. The calculated results showed that process in（b） has lower activation energies than （a）.