Theoretical Study of Aluminum Fluoro-complexes in Extraframework：Simulation of 19F and 27Al NMR

• Main Authors: Cheng-Yao Wu, 吳丞燿
• Other Authors: 江志強
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/vz2h6m

碩士 === 國立臺灣科技大學 === 化學工程系 === 94 === The simulation of the dealumination of zeolite by (NH4)2SiF6(AHFS) treatment, resulted in the Aluminum Fluoro-complexes in extraframework, in which one aluminum and two aluminum complexes were investigated. All the geometries were optimized by using density function theory at the B3LYP/6-31+G* level. A scaling technique is applied to the calculation of 19F NMR properties using both HF and B3LYP methods at the 6-311+G(2df,p) level, and the calculation of 27Al chemical shift and quadrupole coupling constant is performed at the B3LYP/6-311+G(2df,p) level. In addition, the influence of the coordination number, ligand, and hydrogen bond to chemical shift and quadrupole coupling constant were examined. The results demonstrate that, in a variety of isomers, the stability of 4-coordi- nation is more stable than that of 5-coordination or 6-coordination in one Al complexeses. The change of chemical shift of 19F NMR is mainly influenced by coordination number, ligand and hydrogen bond, and the change of chemical shift 27Al NMR is primarily affected by coordination number and ligand. The quadrupole coupling constant is principally influenced by the second shell water; under the same liqand, when the second shell water increases, then reducing thereupon value of Qcc.