The rotational spectrum and structure of the chlorobenzene-neon van der Waals dimer

The chlorobenzene-neon dimer has been studied by Fourier transform microwave spectroscopy. The rotational spectra of three isotopomers were assigned. The structure has the usual stacked configuration with the neon above the aromatic ring. The neon is shifted from above the nominal ring center towards the substituted carbon atom. The distance between this carbon atom and the neon is about 3.57 Angstrom which is about 0.07 Angstrom shorter than this distance in fluorobenzene-Ne and approximately 0.16 Angstrom shorter than in benzene-Ne. Possible interpretations of this pattern are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.