雙分子及參分子組合系統分子間氫鍵之理論研究
| Autor: | Shyh-Jong Chen, 陳世忠 |
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| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 The theoretical study aimed to investigate the combined system which were made up of two and three molecules in the respect of their relative stability of structural conformations and inter-molecular hydrogen bonding problems. The 6-311+G(2d,p) and 6-311++G(3df,2pd) basis sets with B3LYP level and MP2 level at 6-311++G(3df,2pd) basis set, which were selected from Gaussian 03 package, were employed herein. These calculation methods were applied to the combined system of two molecules model including the combined system of between syn-, anti-formic acid and amines; the combined system of dimers constructed with HCO2H, syn-FCO2H and anti-FCO2H, and the combined system of weakly bound dimers between hydrogen fluoride and non-polar/ some polar molecules. The combined of system of three molecules model including the various third molecules on reaction channels of weakly bound complex CO2 ---HF systems, and the combined system of nitric acid-ammonia/ amines as various complexes with water or methanol. All the local minima and transition states are identified by structural optimization and frequency calculations. The result of calculation verifies that all there is inter-molecular hydrogen bonded in all combined molecular or the ion pair-types hydrogen-bonded systems. In addition to using the geometrical structures, vibration frequencies, energy differences and temperature variations, and our newly developed semi-emperical “localized bond analysis method” were also applied to the inter-molecular hydrogen bonding strength determination problem. For the macroscopic consideration Gibbs energy differences are also very important factor for the determination of hydrogen bonding dissociation. From the above-mentioned calculation results of different combined systems. We found that the stability of them and hydrogen bonding formation are directly related to methylation effect, solvent effect and polarization effect. Most conventional H-bonds are formed with the polarized H atom on one side and the electron donation atom, O or N. On the other hand, the H ---C H-bond is seldom found in inter-molecular or intra-molecular H-bonding problems. The strong theoretical evidence developed in this study indicates that the H ---C or H ---N low electronegative connection H-bonds in the FH ---CO, FH ---CNH, and FH ---N2O linear dimers are substantially stronger than the H ---O or H ---N high electronegative connection H-bonds in the FH ---OC, FH ---NCH linear dimers and in the FH ---ON2 bent dimer. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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