ELECTRON-DIFFRACTION STUDY OF STRUCTURE AND INTERNAL-ROTATION IN MOLECULE OF BETA-CHLOROVINYLDICHLOROARSINE

Gas-phase electron diffraction has been used to investigate the geomet ric structure and internal rotation in the molecule of beta-chloroviny ldichloroarsine. It has been found that this compound exists in the ga s phase in the form of the trans isomer with the following parameters (r(a) in angstrom, angles in deg): C=C 1.374, As-C 1.891, As-Cl, 2.197 , C-Cl 1.729, C-H 0.961, angles CCAs 121.0, CCCl 123.1, CAsCl 101.1, C lAsCl 99.1, CCH 127.8; phi = 162.1 is the angle of rotation of the AsC l2 group around the As-C bond (phi = 0 corresponds to eclipsed bisectr ices of the ClAsCl angle and the C=C bond). The first four coefficient s have been calculated for the potential function of internal rotation of the AsCl2 group around the As-C bond: 3.789, -0.805, -0.901, and 0 .137 kJ/mole; the barrier to internal rotation is approximately 7 kJ/m ole.