N_5H_5的结构性能的量子化学研究

Quantum chemistry study on the structure and property of N_5H_5

采用了密度泛函 B3LYP 方法在6-311++G^(**)基组上对 N_5H_5异构体进行了理论计算,得到7种稳定构型,应用自然键轨道理论(NBO)和分子中的原子理论(AIM)分析了这些异构体的成键特征、相对稳定性.N—N键的键长与键临界点的电荷密度存在线性关系,键临界点的电荷密度ρ越大,N—N键的键长就越短.N 原子孤对电子与相邻的氮氮键之间的相互作用是影响氮氮键长变化的主要因素.立体交换排斥能和离域化能是影响异构体相对稳定性的重要因素.G3MP2计算结果表明所有异构体的生成热均为正,环状异构体的能量和生成热高于链状异构体.

Density function B3LYP method with 6-311＋ ＋G^＊＊ basis set was applied to study 7 N5H5 hydronitrogen compounds. Theories of nature bond orbital（NBO）and atoms in molecules （AIM） were used to discuss bond nature and relative stabilities of such conformers. The N-N bond length displays reverse dependence on the charge density in bond critical points obtained. The orbital interaction from lone pairs on nitrogen atoms to germinal N-N bonds can play an important role in the N-N bond length. Furthermore, the NBO calculation implies that relative stabilities of all 7 conformers can be attributed to the steric exchange energy and delocalization energy. In addition, the result derived from G3MP2 shows that the heats of formation of all conformers are positive and the energies and heats of formation of ring-liked conformers are greater than those of chain-shaped conformers.