INFRARED STUDIES OF HYDROGEN-BONDING OF METHANOL IN BINARY-MIXTURES WITH ACETONITRILE

Infrared nu(OH) spectra of binary mixtures of methanol and acetonitrile have been studied over the whole concentration range. It has been shown that the overall band profile is influenced by a diverse range of hydrogen-bonded methanol aggregates (CH3OH)n with n extending to at least 4 along with at least two CH3OH/CH3CN molecular complexes (i.e. 1:1 and 2:1 CH3OH:CH3CN species). Band intensities and normalised concentrations of the various aggregates have been computed using a band fitting procedure and have been compared with the respective values expected from a multiple equilibrium model for complex formation. It is found that for the 1:1 complex behaviour it is essential to include the effects of the methanol n-mer network. It is emphasised that different perspectives on a given set of molecular interactions may be achieved by examination of both infrared and Raman spectra of the same system.