Rotational spectrum and molecular properties of pyridine...xenon.

The rotational spectra of six isotopologues of pyridine-xenon, two isotopes of the nitrogen atom ((14)N and (15)N) in pyridine with three isotopes of the rare gas atom ((129)Xe, (131)Xe, and (132)Xe) have been measured by pulsed jet Fourier transform microwave spectroscopy. The complex has a structure with the xenon atom located in the plane of symmetry perpendicular to the aromatic ring plane. Its distance from the center of mass of pyridine is 3.81 A, and it is tilted--with respect to the c principal axis of pyridine--by 7 degrees toward the N atom. The (14)N and (131)Xe nuclear quadrupole coupling constants have been determined for the isotopologues containing these nuclei. Information on the dynamics of the Xe van der Waals motions was obtained from the centrifugal distortion and from the changes in the planar moments of inertia in going from pyridine to pyridine...Xe.