Theoretical Study and AIM Analysis of C-H...X Hydrogen Bonded Complexes

• Main Authors: Juan, Ning, 阮寧
• Other Authors: Ito Chao, Chi-Tang Tsai
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/40586391408213973926

碩士 === 中國文化大學 === 應用化學研究所 === 86 === Abstract The research was to study C-H…X (X=N, O) intermolecular hydrogenbonding interactions for a series of C-H …X hydrogen-bonded complexes using theoretical calculations. The work was divided into three main areas:(1) The first area, we examined the potential energy surface of the C-H…Xhydrogen bonded complexes HCCH…OH2, HCCH…NH3, HCCCN…OH2 and HCCCN…NH3 to locate all the minimum energy structures using ab initio HF/6-31G*, B3LYP/6-31+G** and MP2/6-31++G(2d,2p) calculations. The electron densityAIM (atoms in molecules) method was employed to analyze the effects ofgeometric parameters (H…X distance) upon the degree of H-bonding interactions for the series of structures(2) The second area involved semi-empirical methods, AM1 and PM3 calculations,on the series of H-bonded complexes. The results obtained, this is, their interaction energies, are correlated to single molecule's physical properties such as gas- phase substituent acidity or basicity (GA or GB), proton affinity(PA),Hammett sigma parameter (s) and molecular electrostatic potentials (MEP),and the correlation is compared to that of corresponding ab initio studies.We studied in two directions: one is to change the type of proton donor(C(sp)-H, C(sp2)-H and C(sp3)-H) in the proton-donor…ammonia complexes, and the other is to change the proton acceptor (O-acceptor, N- acceptor and p-acceptor) in the acetylene…proton-acceptor complexes.(3) Finally, we applied AIM method to study the relationship betweeninteraction energies and the electron density on the hydrogen bond critical point for the proton-donor …ammonia complexes.