Properties of a complex of carbon dioxide and chlorine monofluoride from rotational spectroscopy: Identification of an extremely weak interaction

The ground-state rotational spectra of three isotopomers, (CO2)-C-12-O-16...(ClF)-Cl-35,(CO2)-C-12...(ClF)-Cl-37 and (CO2)-C-13...(ClF)-Cl-35, of a complex formed by carbon dioxide with chlorine monochloride have been observed by pulsed-nozzle, Fourier-transform microwave spectroscopy. The following values of the spectroscopic constants B-0, D-0, H-0, chi(Aa)(Cl) and M-bb(Cl) have been determined for this linear (or nearly linear) molecule. [GRAPHICS] Interpretation of the spectroscopic constants reveals that the nuclei lie in the order OCO...CIF, with r(O...Cl) = 2.699(2) Angstrom, and that the intermolecular band is very easily distorted both radially and angularly. A comparison of the series B HF and B...CIF for B = Ar, N-2, CO or CO2 establishes that CO2...ClF is anomalous in respect of the strength of its binding. (C) 1997 Elsevier Science B.V.