Correlation between Bond-Length Change and Vibrational Frequency Shift in Hydrogen-Bonded Complexes Revisited

The correlation between the X - H bond-length change and the corresponding X - H stretching frequency shift upon X - H center dot center dot center dot Y (Y is an electron donor) hydrogen bond formation is the basis for the spectroscopic detection and investigation of the hydrogen bond. However, this view has been questioned in a recent report, suggesting that the widely accepted correlation between the bond-length change and the frequency shift in hydrogen-bonded complexes is unreliable (McDowell, S. A. C.; Buckingham, A. D. J. Am. Chem. Soc. 2005, 127, 15515.). In this work, several robust computational methods have been used to investigate this issue. The results clearly show that a computational artifact leads to the conclusion incorrectly reported by McDowell and Buckingham and that the correlation between the X - H bond-length change and the corresponding X - H stretching frequency shift is still very good in the hydrogen-bonded complexes studied.