Aromatic-rare gas complexes: The microwave spectrum and structure of the fluorobenzene-neon dimer

The rotational spectrum of the fluorobenzene-neon complex was assigned. The structure of the complex was deduced from the rotational constants of the C6H5F-Ne-20, C6H5F-Ne-22, and C6D5F-Ne-20 species. The dimer has C-s symmet ry. The neon atom sits nearly above the center of the fluorobenzene at a pe rpendicular distance of 3.422(1) Angstrom. It is shifted 0.13(1) Angstrom f rom the center of the ring toward the fluorinated carbon atom. The structur e is compared with a number of related aromatic-rare gas complexes (rare ga s = Ne or Ar). Trends are discussed in view of dispersion, polarization, an d repulsive forces.