MICROWAVE SPECTROSCOPIC INVESTIGATION OF THE WEAKLY BOUND DIMER CARBON-MONOXIDE CHLORINE, OCCL2

The rotational spectrum of the van der Waals complex OCCl2 has been observed in the frequency range 5-12 GHz using a cavity-pulsed microwave Fourier transform spectrometer. The isotopomers investigated were (OCCl2)-Cl-35, (OCClCl)-Cl-37-Cl-35, (OCClCl)-Cl-35-Cl-37, (OCCl2)-C-13-Cl-35, (OCClCl)-C-13-Cl-37-Cl-35, (OCClCl)-C-13-Cl-35-Cl-37, and (OCCl2)-O-18-C-13-Cl-35. It is established that the complex is linear in the ground vibrational state, and a complete substitution (r(s)) structure has been obtained. The nuclear quadrupole hyperfine structures due to the Cl-35 and Cl-37 nuclei have been resolved, yielding the corresponding nuclear quadrupole coupling constants. The differences in these constants between the inner and outer Cl nuclei, along with the derived geometry and the relatively low centrifugal distortion constants, are consistent with a picture of a rather rigid complex with a significant charge redistribution in the Cl2 monomer on complexation with CO.