QUANTUM-CHEMICAL CALCULATIONS AND CL-35 NQR STUDY OF THE MOLECULAR-STRUCTURE OF TRICHLOROACETYL HALIDES AND TRICHLOROACETALDEHYDE

An optimal geometry of CCl3C(O)X molecules (X = H, F, Cl, Br, and I) i s determined by the MNDO quantum chemical method. According to the res ults of calculations, the molecules in the free state have an eclipsed conformation with a syn-peri-planar position of the oxygen atom and o ne of the chlorine atoms of the trichloromethyl group. However, as fol lows from the Cl-35 NQR spectra at different temperatures, in the crys tal state of CCl3C(O)X this conformation is distorted under the influe nce of intermolecular interactions due to the torsional rotation of th e CCl3 group around the C-C bond. Indicatory potentialities of the NQR method with respect to the structural features that are due to crysta llographic effects are discussed.