The CO stretching frequencies in the Raman spectra of 0.10 M solutions of tetramethylurea in seventeen solvents have been recorded. These frequencies exhibit a linear relationship with the solvent electron acceptor number. Comparison of the slopes of these lines and those obtained from analyzing literature data of ν(CO) reveals a correlation with the bond polarity. A linear correlation between (νhexane -νsoln)/νhexane and the solvent acceptor number is also shown. The slopes of these latter plots can be related to νhexane and it is suggested that this approach be used to explain the specific solvent-solute interaction contributions to solvent-induced vibrational frequency shifts. This method is compared with the solvato-chromic method and it is shown that solvent acidity strongly influences the observed vibrational frequency shifts for the CO moiety of tetramethylurea.
|Original language||English (US)|
|Number of pages||8|
|Journal||Spectrochimica Acta - Part A Molecular Spectroscopy|
|State||Published - 1988|
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