On the Utility of Infrared Intensity Enhancement, a Sensitive Experimentally Accessible Marker, in Investigating Trends for Hydrogen-Bonded Complexes

A computational study of model complexes of XH (X = halogen) and YX-H (X = N, C, O, S, Se; Y = halogen, N, P, NC3H3) hydrogen-bonded to a Lewis base Z which includes N-bases (such as NCH), BF, H2O and CN- was undertaken to investigate trends for selected structural and spectroscopic parameters. Variation in the natural bond orbital (NBO) charge re-distribution was also investigated. The results suggest that infrared intensity enhancement of the X-H stretching mode is a sensitive experimentally accessible marker and was found to be inversely correlated with the polarity of the X-H bond (for fixed Z).