INFRARED-SPECTRA, RELATIVE STABILITY, AND AB-INITIO CALCULATIONS OF THE CD3CL-CENTER-DOT-HCL VAN-DER-WAALS COMPLEX OBSERVED IN LIQUEFIED ARGON

The mid-infrared (4000-400 cm-1) and far-infrared (300-10 cm-1) spectra of several methyl-d3 chloride/hydrogen chloride mixtures, dissolved in liquefied argon (95-117 K) are discussed. In all spectra, experimental evidence was found for the existence of a 1:1 van der Waals complex. By use of a temperature study, the complexation enthalpy of the CD3Cl.HCl complex was determined to be -7.8 +/- 0.4 kJ mol-1. At higher concentrations of HCl a new absorption band is observed which has to be assigned to a 1:2 bonded complex. Ab initio calculations at the HF/6-31G** level show that the angular geometry of the CD3Cl.HCl species is similar to the geometry of the HCl dimer, i.e. that the complex has an approximate L-shape, in which the electron acceptor HCl molecule is bonded through its hydrogen atom to the chlorine atom of the electron donor methyl-d3 chloride molecule.