Hybrid-Density Functional Theory, MO Study, and NBO Interpretation of Conformational Behaviors of 2-Halo-1,3-Dioxanes and Their Dithiane and Diselenane Analogs

摘要: Abstract The impacts of the endo- and exo-anomeric effects (endo-AE exo-AE), electrostatic interactions, steric repulsions on conformational behaviors 2-fluoro-1,3-dioxane, -dithiane, -diselenane (1–3), 2-chloro-1,3-dioxane, (4–6), 2-bromo-1,3-dioxane, (7–9) have been analyzed by means natural bond orbital (NBO) interpretation, hybrid density functional theory (B3LYP/6–311+G**), ab initio molecular (HF/6–311+G**) based methods. Both methods showed axial preference for compounds 1–9. calculated Gibbs free energy difference (Geq–Gax) values (i.e.ΔGeq−ax) between equatorial conformations increases from compound 1 to 2 but decreases 3. Contrary trend observed 1–3, ΔGeq−ax decrease 4 6 7 9. Similar trends were also corresponding AE values. On co...