Bonding energies of rare gases with aromatic molecules: rotational spectrum and dynamics of pyridazine?neon

The rotational spectrum of the pyridazine(((Ne complex, a species observable in supersonic expansions, has been measured by free jet absorption millimeter wave spectroscopy. The equilibrium configuration, dynamics and dissociation energy have been deduced from the spectroscopic constants. The equilibrium distance of Ne with respect to the center of mass of the molecule is 3.26 A, with the Ne atom tilted by 5.8° from the perpendicular to the center of mass of the ring towards the mid-point of the two nitrogen atoms. The dissociation energy is estimated, from the centrifugal distortion constant DJ, to be ca. 0.8 kJ mol?1.