HEAVY ATOM LARGE AMPLITUDE MOTION IN RG-CYCLOPROPANE COMPLEXES

Author Institution: Department of Chemistry, University of AlbertaRotation-tunneling spectra of the van der Waals Complex Ne-cyclopropane, and pure rotational spectra of Ar-cyclopropane and Kr-cyclopropane, were measured with a Fourier transform microwave spectrometer in the frequency range from 4 to 19 GHz. The observed transitions are all of {a}-type and are in accord with those of prolate symmetric top molecules where the rare gas atom is positioned on the $C^{3}$ axis of the cyclopropane submmit above its symmetry plane. Effective separations between the center-of-mass of cyclopropane and the rare gas atoms were obtained from the ground state rotational constants- Transitions of two isomers were observed for complexes that contain monodeuterated cyclopropane. In the case of the parent Ne-cyclopropane complex, and its $^{22}Nc$-and mono $^{13}C$-isotopomers, all transitions appeared as doublets. This is attributed to a tunneling internal rotation motion of the cyclopropane unit within the complex