Infrared spectroscopy of protonated methanol clusters H+(methanol)n in benzene solution has been studied by Stoyanov et al. (Chem. Eur. J. 2008, 14, 3596 - 3604). In H+(methanol)n, one-dimensional hydrogen-bonded chains are formed, and the OH group at each end of the hydrogen-bonded chains forms a π-hydrogen bond with the solvent benzene. To investigate the convergence process from the gas phase to the liquid phase through the progression of microsolvation, we performed infrared spectroscopy of gas-phase H+(methanol)n-(benzene)m (n = 2−5, m = 1-3) clusters and compared the results with those in the benzene solutions. The π-hydrogen bonded OH stretching frequencies show a significant difference from the benzene solutions for m = 1, but the difference is greatly reduced for m = 2. The third benzene molecule directly solvates the protonated site, but there is still a non-negligible difference from the benzene solutions, suggesting that at least two benzene molecules are effectively involved in the direct solvation of the protonated site of the cluster in the benzene solutions.
