Vibrational spectra and normal coordinates analysis of cis-FHCCHI

The gas-phase infrared spectrum of cis-1-fluoro-2-iodoethene has been examined at medium resolution in the range 200–6500 cm−1, leading to the identification of 11 fundamentals. The remaining one, ν9, has been predicted at 150.0 cm−1 from observed bands involving this level, selected from a number of first overtone, combination and hot bands. The assignment, assisted by quantum chemical calculations corrected where necessary by anharmonic resonances, is consistent all over the region investigated. Additional spectroscopic parameters, obtained from the analysis of the partially resolved rotational structure of some bands, are compared with the corresponding calculated values.