The water-methanol complexes. Matrix induced structural conversion of the 1-1 species

The infrared spectrum of the CH3OH:H2O heterodimer trapped in solid argon has been identified from experiments at low concentration in both dopants and by exploring a large domain of the CH3OH/H2O molar ratio. The touchstone for the identification of its structure is the frequency of the νCO mode, measured at about 1031 cm−1, which implies a role of proton acceptor for the metahnol subunit. Ab initio calculations at the MP2 level and also using the DFT technique provide convincing support for the existence of the CH3HO/3.HOH form. This conclusion agrees with that drawn in the gas phase but is opposite to that reached in nitrogen matrix in which a sole CH3OH/3.OH2 structure has been identified.