Resumen de Mechanism of isomerization in dithietane-1,3-dioxide

J. Guillermo Contreras, Lorena Gerli-Candia, S. Marcela Hurtado, Sandra T Madariaga

• The cis ¤ trans isomerization reaction of dithietane-1,3-dioxide ( DTDO) has been studied by means of theoretical methods in the framework of molecular orbital theory. The energetics of this reaction was obtained with several basis sets and levels including both polarization and diffuse functions. Electronic correlation has been taken into account by applying second-order perturbation Mller-Plesset theory. The thermodynamics indicates that both isomeric forms are in almost the same concentration in the gas phase, whereas in solution in more polar solvents, the cis form becomes more important. The transition state for the cis ¤ trans interconversion reaction has been fully characterized and the activation energy has been calculated to be 47.8 kcal/mol in the gas phase. In general, the solvent, simulated by the PCM model, lowers Ea as its polarity increases, and in DMSO (e = 46.7) Ea goes down by ca. 20 kcal/mol. The calculated ¹H-NMR chemical shifts are consistent with the experimental data. The predicted 17O and 33S-NMR spectra should allow to distinguish between the two conformations