Conformational analysis of 2-[(4-substituted-phenyl)seleno]-1,3-dithianes: |a theoretical approach

Abstract

In this study the conformational analysis of 2-(4-substituted-phenyl)seleno-1,3-dithiane with H, Cl, F, CH3, CF3, NO2, OCH3 and N(CH3)2 substituents have been studied computationally both in gas phase and in solvent with the semi-emprical PM3 method and ab initio HF/6-31G* basis sets. The optimized geometries have been discussed in terms of endo and exo anomeric effects and their presence in the axial conformers have been confirmed. The conformational free energies have been calculated in gaseous phase in solvent. Comparison between experimental and calculated values has shown that PM3 as well as HF/6-31G* can be used confidentially to treat conformational equilibrium for cyclohexane derivatives with S and Se.