INFRARED-SPECTROSCOPY OF THE MOLECULAR-HYDROGEN SOLVATED CARBONIUM-IONS, CH5+(H-2)(N) (N=1-6)

The infrared spectra for the molecular hydrogen-solvated carbonium ions, CH5+(H2)n, (n = 1-6) in the frequency range of 2700-4200 cm-1 are presented. Spectroscopic evidence was found in support of the scrambling of CH5+ through the large amplitude motions such as the CH3 internal rotation and the in-plane wagging motion of three-center two-electron bond. More importantly, the scrambling motions of CH5+ cores were slowed down considerably by attaching the solvent H2 molecules to the core ion. The complete freezing of the scrambling motions was found when the first three H2 molecules were bound to the CH5+ core. A good agreement between the experimental and the theoretical predictions was found in the dynamics of CH5+. © 1995 American Institute of Physics.