DETERMINATION OF THE MOLECULAR-STRUCTURE OF S-TRIOXANE BY NMR OF PARTIALLY ORIENTED MOLECULES

The H-1 and C-13 NMR spectra of s-trioxane partially oriented in three nematic solvents were analysed, and the measured dipolar coupling constants, corrected for harmonic vibrations and for correlated deformation, were used to obtain information about the r(alpha), structure of the molecule. It is concluded that the s-trioxane molecule oscillates between two equivalent chair conformers and the methylene protons are tilted outwards from the threefold symmetry axis. The optimized values for the geometric parameters are 1.111 (2) Angstrom for the CH bond length, 110.3 (3)degrees for the HCH bond angle and -2.1 (3)degrees for the methylene rocking coordinate.