Molecular Geometry of Trans, Trans-1,2-Dimethyl- and of Trans, cis-1,2-Dimethyl-Ethylenesulfite; a Gas Diffraction Study

The configuration of trans, trans-1,2-dimethyl and of trans, cis-1, 2-dimethylethylene-sulfite, as suggested by NMR, is in agreement with electrondiffraction results in the gas phase. The best fit to the observed diffraction intensities was obtained with a non-planar sulfite ring, ϕmax = 42.6°. In the trans, cis derivative the methyl groups are pseudo-equatorial, whereas in the trans, trans compound one methyl is pseudo-axial, the other pseudo-equatorial. Although these are the best, static representations of the molecules, mixtures containing several conformations cannot be excluded.