Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5416883 | Journal of Molecular Structure: THEOCHEM | 2010 | 6 Pages |
Abstract
NBO analysis, hybrid-density functional theory (hybrid-DFT: B3LYP/6-311+Gââ//HF/6-311+Gââ) and ab initio molecular orbital (MO: MP2/6-311+Gââ//HF/6-311+Gââ) based methods were used to study the anomeric effects (AE) on the stability of the cis- and trans-stereoisomers of 1,4,5,8-tetraoxadecalin (1), 1,4,5,8-tetrathiadecalin (2) and 1,4,5,8-tetraselenadecalin (3). The B3LYP/6-311+Gââ//HF/6-311+Gââ results revealed that the cis-stereoisomers of compounds 1-3 are more stable than their trans-stereoisomers by about 4.26, 1.03 and 0.70 kcal molâ1, respectively. Also, the cis-stereoisomers of compounds 1-3 are more stable than their trans-stereoisomers by about 4.18, 2.11 and 01.18 kcal mol-1, respectively, as calculated at the MP2/6-311+Gââ//HF/6-311+Gââ level of theory. In addition, HF/6-311+Gââ//HF/6-311+Gââ results revealed that the Gibbs free energy difference (Gcis â Gtrans) values (e.g. GFEDcis-trans) between the cis- and trans-stereoisomers decrease from compound 1 to compound 3. On the other hand, the NBO analysis of donor-acceptor (bond-antibond) interactions revealed that the anomeric effects (AE) for compounds 1-3 are â22.08, â17.84 and â13.22 kcal molâ1, respectively. The decrease of the AE could fairly explain the decrease of the GFEDcis-trans from compound 1 to compound 3. On the other hand, the decrease of the donor-acceptor interactions associated with LPaxM1 â ÏâC9-O8 electronic delocalizations could fairly explain the increase of occupancies of LPaxM1 non-bonding orbitals and the decrease of occupancies of ÏâC9-O8 anti-bonding orbitals from the cis-stereoisomers of compound 1 to compound 3.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Davood Nori-Shargh, Neda Hassanzadeh, Meisam Kosari, Sasan Sharifi,