Infrared photodissociation spectra and solvation structures of Mg+(CH3OH)n (n=1–4)

The infrared photodissociation spectra of mass-selected Mg+(CH3OH)n (n=1–4) are measured and analyzed with the aid of density functional theory calculations. Hydrogen bonding between methanol molecules is found to be absent in Mg+(CH3OH)3, but detected in Mg+(CH3OH)4 through characteristic frequency shifts of the OH stretch of methanol. The maximum number of the methanol molecules that can be directly bonded to the Mg+ ion is limited to three and the fourth molecule starts to fill the second solvation shell. The vibrational spectroscopy provides clear evidence for the closure of the first shell at n=3.