A re-investigation of the molecular structure of trifluoroacetic acid by means of gas phase electron diffraction

Analysis of the electron diffraction patterns of trifluoroacetic acid at 140°C indicates the existence of one conformation with the CF₃-group rotated 17.3± 0.9° from a position with a fluorine atom eclipsed with respect to the CO bond. The data does not exclude the possibility of free internal rotation but it seems improbable.The important bond lengths, r_g(1), and bond angles with their standard deviations in parentheses, are: C-F: 1.325 (0.003), C-C: 1.546 (0.005), CO: 1.192 (0.003), C-O: 1.353 (0.014) Å, C-C-F: 109.5 (0.3), C-CO: 126.8 (0.8), C-C-O: 111.1 (0.9)°.