The Conformation of Racemic 4,6-Dimethyl Trimethylene Sulfite by Gas Phase Electron Diffraction

Abstract

The molecular geometry of the racemate trans-4,6-dimethyl trimethylene sulfite has been studied in the gas phase by electron diffraction. Six trial conformations were examined by least squares fitting of the intensity data. A significance test applied to the fits obtained for each of the six static models tested indicate that the best single representation of the molecule has a chair conformation, although a mixture containing other conformations could not be definitely eliminated. It was not possible to conclusively discriminate between an axial or an equatorial S=O bond, although the axial position is favored. The following bond distances (rg values) and angles were determined: C—H = 1.119 ± 0.020, C—C = 1.505 ± 0.014, C—O = 1.413 ± 0.013, S=O = 1.480 ± 0.022, S—O = 1.622 ± 0.009 Å; [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]. The following angles were assumed to be tetrahedral: [Formula: see text], [Formula: see text], [Formula: see text]. The errors are estimated to be at the 95% confidence level. The molecular parameters are in agreement with those of trimethylene sulfite.