FT-IR spectral data and ab initio calculations for haloketenes

Photolysis of haloacetyl chlorides isolated in cryogenic xenon matrix generates hydrochloric acid which is growing at the same rate as a ketene-like moiety. This last species is found to be different in the experiment involving fluoroacetyl and chloroacetyl chloride, from Fourier transform infrared (FT-IR) spectral results. The frequencies and intensities of the corresponding FT-IR spectral features are compared with the theoretical values obtained from ab initio calculations for fluoroketene HFCCO, chloroketene HClCCO and dichloroketene ClClCCO. The theoretical results give a satisfactory account of the haloketene HXCCO (X=F or Cl) assumption.