Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5418103 | Journal of Molecular Structure: THEOCHEM | 2008 | 4 Pages |
Abstract
The effect of methyl group on the cooperativity of CH···O blue-shifted hydrogen bond in HCHO-HCHO-HCHO cyclic complex has been studied with quantum chemical calculations at the MP2/6-31+G(d,p) level. We report herein the optimized geometries of the stable structures, their vibrational frequencies, NMR chemical shifts, stabilization energies, and binding energies. The cooperativity of CH···O blue-shifted hydrogen bond varies from â0.57 kcal/mol in triformaldehyde through â0.65 kcal/mol in trimethyltriformaldehyde to â0.79 kcal/mol in trifluorotriformaldehyde. The result indicates that the methyl group has a little enhancing effect on the cooperativity of CH···O blue-shifted hydrogen bond in the cyclic complex. A negative nonadditivity of methyl group is evaluated in enhancing the cooperativity of three CH···O blue-shifted hydrogen bonds. In the formation of the CH···O blue-shifted hydrogen bond, the methyl group in the proton-acceptor plays a positive contribution, whereas that in the proton-donor plays a negative contribution.
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Qingzhong Li, Haiping Liu, Xiulin An, Baoan Gong, Jianbo Cheng,