Molecular structure of ArDF: An analysis of the bending mode in the rare gas–hydrogen halides

The rotational spectrum of the ArDF van der Waals molecule has been assigned using pulsed Fourier transform microwave spectroscopy in a Fabry-Perot cavity with a pulsed supersonic nozzle as the molecular source. The DF nuclear spin–nuclear spin and D nuclear quadrupole coupling constants are 12.5(11) and 194.7(20) kHz, respectively. These constants yield equivalent structural information and are used together with the rotational constant to obtain the structure of ArDF. The rotational spectrum of ArHF was also re-examined and the HF spin–spin constant found to be 49.0(19) kHz. The structure of ArHF was then obtained from the rotational and HF spin–spin constants. Finally, the vibrationally averaged angles in 14 complexes of the type X–H(D)Y (X=Ar, Kr, or Xe; Y=F, Cl, or Br) are calculated using a multipole potential and compared with experiment. The agreement between the observed and calculated angles is very good.