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采用密度泛函理论,在B3LYP/6-311+G~(**)水平上对C_3N_3(NH_2)_3、[C(O)NH]_3、H_2O 3种单体在气相中形成的双分子氢键作用体系进行构型优化和频率计算。通过几何优化得到一系列含多个氢键的复合物。频率分析表明,与单体相比,体系形成氢键作用后,参与氢键形成相关的键的红外谱带位置和振动强度都发生明显的变化,其中C_3N_3(NH_2)_3-[C(O)NH]_3体系中N8—H9键的红移最明显。同时,通过B3LYP/6-311+G~(**)和MP2/6-311+G~(**)水平计算的含基组重叠误差(BSSE)校正的氢键相互作用能分析表明,C_3N_3(NH_2)_3-[C(O)NH]_3氢键体系的相互作用能最大,其次是([C(O)NH]_2)_2体系,采用MP2/6-311+G~(**)方法计算的相互作用能分别达到-14.171 kcal·mol~(-1)和-10.217 kcal·mol~(-1)。另外,通过自然键轨道理论揭示氢键相互作用的本质。
At B3LYP / 6-311 + G ~ (**) level, the molecular weights of three molecules of C_3N_3 (NH_2) _3, [C (O) NH] _3 and H_2O formed in the gas phase were investigated by using density functional theory Key role of the system configuration optimization and frequency calculation. Through geometric optimization, a series of complexes with multiple hydrogen bonds are obtained. The frequency analysis showed that the positions of the infrared bands and the vibration intensity of the bonds involved in the formation of hydrogen bonds changed significantly after the system formed hydrogen bonds compared with the monomers. Among them, C_3N_3 (NH_2) _3- [C (O) NH] _3 system N8-H9 bond redshift the most obvious. At the same time, the hydrogen bond interaction energy calculated by B3SE / B3-1 + G ~ (**) and MP2 / 6-311 + G ~ (**) levels with BSSE correction shows that C_3N_3 (NH2) _3- [C (O) NH] _3 hydrogen bond system is the largest, followed by the [C (O) NH] _2) _2 system using MP2 / 6-311 + G ~ The interactions calculated by this method can reach -14.171 kcal · mol ~ (-1) and -10.217 kcal · mol ~ (-1), respectively. In addition, the nature of the hydrogen bond interaction is revealed by the theory of natural bond orbital.