Infrared spectroscopy of the molecular hydrogen solvated carbonium ions, CH+5(H2)n (n=1–6)

The infrared spectra for the molecular hydrogen‐solvated carbonium ions, CH+5(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 CH+5 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 CH+5 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 CH+5 core. A good agreement between the experimental and the theoretical predictions was found in the dynamics of CH+5.