Hybrid-Density Functional Theory, MO Study, and NBO Interpretation of Conformational Behaviors of 2-Halo-1,3-Dioxanes and Their Dithiane and Diselenane Analogs
| Autor: | Gholam Abbas Kasaei, Fatemeh Azarakhshi, Salma Karamad, Davood Nori-Shargh, Hadis Zamani Ganji, Nasrin Masnabadi, Maryam Abbasi Eshlaghi |
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| Rok vydání: | 2012 |
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| Zdroj: | Phosphorus, Sulfur, and Silicon and the Related Elements. 187:305-320 |
| ISSN: | 1563-5325 1042-6507 |
| DOI: | 10.1080/10426507.2011.610847 |
| Popis: | The impacts of the endo- and exo-anomeric effects (endo-AE and exo-AE), electrostatic interactions, and steric repulsions on the conformational behaviors of 2-fluoro-1,3-dioxane, -dithiane, -diselenane (1–3), 2-chloro-1,3-dioxane, -dithiane, -diselenane (4–6), and 2-bromo-1,3-dioxane, -dithiane, -diselenane (7–9) have been analyzed by means of natural bond orbital (NBO) interpretation, hybrid density functional theory (B3LYP/6–311+G**), and ab initio molecular orbital (HF/6–311+G**) based methods. Both methods showed the axial preference for compounds 1–9. The calculated Gibbs free energy difference (Geq–Gax) values (i.e.ΔGeq−ax) between the axial and equatorial conformations increases from compound 1 to compound 2 but decreases from compound 2 to compound 3. Contrary to the trend observed for compounds 1–3, the calculated ΔGeq−ax values decrease from compound 4 to compound 6 and from compound 7 to compound 9. Similar trends were also observed for the corresponding calculated AE values. On the co... |
| Databáze: | OpenAIRE |
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