van der Waals complex of dimethyl ether with carbon dioxide

The 1: 1 complex between dimethyl ether and carbon dioxide was studied experimentally in solutions in liquid argon, using infrared spectroscopy, and theoretically, using ab initio calculations at the MP2/6-311 ++G(d,p) level. The complex is formed through the interaction of the dimethyl ether oxygen atom with the CO2 carbon atom, with the CO2 perpendicular to the 2-fold axis of dimethyl ether, in the plane of the heavy atoms of the latter. Observed vibrational bands are in good agreement with the predicted vibrational frequencies. The standard complexation enthalpy of the complex in liquid argon was determined from a temperature dependent study of the spectra and was found to be - 8.0(3) kJ mol(-1). Some aspects of the Fermi resonance between the symmetric stretch and the first overtones of the two bending modes of the CO2 moiety of the complex are discussed.