N-甲替甲酰胺-水的氢键团簇的从头计算研究

利用从头计算方法在MP2 / 6 31+G 和MP2 / 6 311++G(d ,p)水平上对N 甲替甲酰胺 (NMF) 水氢键团簇进行了研究 .计算给出了所有中性和离子化NMF H2 O团簇的优化结构、解离通道以及解离能 .对于N 甲替甲酰胺 ,顺式结构比反式结构具有更低的能量 .对于质子化的NMF ,质子倾向于连接在甲替甲酰胺的氧原子上 .计算结果表明 ,NMF的顺式和反式构型都可以与水分子形成线型的氢键结构 .尽管NMF反式结构比顺式结构能量高 ,但由于反式结构能与水分子形成双氢键 ,因此能更稳定的存在 .N 甲替甲酰胺 水团簇电离后 ,无论顺式和反式结构均有质子化产物生成 .

Ab initio Study of the Hydrogen-bonded Clusters of N-methylformamide-water

The N-methylformamide(NMF)-water clusters were studied by ab inito calculations at MP2/6-31+G ** and MP2/6-311++G(d, p) levels. The equilibrium geometries and the dissociation channels and dissociation energies of both neutral and ionic NMF-H 2O clusters are presented. For N-methylformamide, cis-form has lower energy than trans-form. In NMFH+, the proton prefers to link with the O atom of N-methylformamide. The results show that both cis- and trans- form of NMF can form a linear hydrogen bond with water. Although the energy of trans-NMF is higher than cis-NMF, trans-form exits more stably because it can form a double hydrogen bond with water. After the ionization of the NMF-H 2O cluster, both the cis- and the trans-form will produce protonated products.