First principles calculations of enthalpy and O-H stretching frequency of hydrogen-bonded acid-base complexes

Understanding the acid-base interactions is important in surface science as it helps to rationalize materials properties such as wetting, adhesion and tribology. Quantitative relation between changes in enthalpy ($\Delta$H) and frequency shift ($\Delta\nu$) during the acid base interaction is particularly important. We investigate $\Delta$H and $\Delta\nu$ of twenty-five complexes of acids (methanol, ethanol, propanol, butanol and phenol) with bases (benzene, pyridine, DMSO, Et$_2$O and THF) in CCl$_4$ using intermolecular perturbation theory calculations. $\Delta$H and $\Delta\nu$ of complexes of all alcohols with bases except benzene fall in the range from -14 kJ/mol to -28 kJ/mol and 215 cm$^{-1}$ to 523 cm$^-1$, respectively. Smaller values of $\Delta$H (-2 to -6 kJ/mol) and $\Delta\nu$ (23 to 70 cm$^{-1}$) are estimated for benzene. For all the studied complexes, $\Delta$H varies linearly (R$^2$ ? 0.974) with $\Delta\nu$ yielding the average slope and intercept of 0.056 and 1.5, respectively. Linear correlations were found between theoretical and experimental values of $\Delta$H as well as $\Delta\nu$ and are concurrent with the Badger-Bauer rule.