The microwave spectrum of an unstable molecule: Chloroketene ClHCCO

Abstract

The microwave spectra of four isotopic species of the unstable molecule chloroketene ClHCCO have been observed from the flow pyrolysis of monochloroacetyl chloride and from the pyrolytic reaction of dichloroacetyl chloride with zinc metal. The spectra, which consist only of b-type transitions, were observed in the frequency range 26.5–80 GHz. Accurate rotational constants and quartic and sextic centrifugal distortion constants have been obtained for all isotopes. Large numbers of perturbations have been observed in the chlorine quadrupole hyperfine structure; consequently, the complete quadrupole coupling tensor has been evaluated. The dipole moment has been measured. The molecule has been shown to be planar, and a partial r0 structure has been determined.