MICROWAVE SPECTRUM, STRUCTURE AND DIPOLE MOMENT OF DIFLUOROPROPADIENONE

Article abstract of DOI:10.1016/0022-2860(90)80470-5

The microwave spectra of the normal and two monosubstituted isotopomers of difluoropropadienone were observed and assigned in the 26.5-40.0 GHz frequency region.For the normal species, the rotational constants were determined to be A=11558.126 +/- 0.004, B=2023.911 +/- 0.001 and C=1720.649 +/- 0.001 MHz.Comparably precise results were obtained for the carbonyl 13C and 18O species.Stark effect measurements led to a total electric dipole moment of μ_T=0.671 +/- 0.012 D with components of μ_a=0.418 +/- 0.013 D and μ_b=0.525 +/- 0.003 D.In contrast with the parent propadienone molecule, the difluoro species shows no evidence of large amplitude tunneling motions.However, the data show clearly that the molecule is strongly distorted from C_2v symmetry with a cumulenone chain that is bent similarly to that in propadienone.