Rotational Spectrum, Dynamics, and Bond Energy of the Oxirane···Krypton van der Waals Complex

From the free jet millimeter-wave spectra of four isotopomers of the weakly bonded oxirane···Kr complex, information on the equilibrium conformation, dynamics, and dissociation energy has been deduced. A C_s symmetry is found for the complex, with Kr lying in the σ_v plane of symmetry of oxirane. The equilibrium distance of Kr with respect to the center of mass of bare oxirane is 3.67 Å, with Kr tilted 13.6° from the perpendicular to the center of mass of the ring toward the oxygen atom. The dissociation energy is estimated, from the centrifugal distortion constant D_J, to be ca. 3.1 kJ/mol.