Stabilization in neutral bicyclic sulfoxide compounds

Density Functional Theory (DFT) calculations at the B3LYP/6-31+G∗ level have been performed on 5-thiabicyclo[2.1.1]hex-2-ene S-oxide derivatives. The geometrical and electronic properties of the compounds have been analyzed in order to explain the favored stability of the exo configuration. Isodesmic reactions at the Gaussian-G2 theory yielded the exo conformer as the most stable one. Moreover, the NMR chemical shift parameters (GIAO method) together with the Atoms in Molecules theory reveal an stabilization of the S atom with the double bond for the exo configuration, in agreement with the experimental results. c © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 322–327, 2000