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Updated: Jun 23, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Redshift or adduct stabilization--a computational study of hydrogen bonding in adducts of protonated carboxylic acids
Solveig Gaarn Olesen1, Steen Hammerum
1De partment of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
Abstract:
It is generally expected that the hydrogen bond strength in a D-H(***)A adduct is predicted by the difference between the proton affinities (DeltaPA) of D and A, measured by the adduct stabilization and demonstrated by the infrared (IR) redshift of the D-H bond stretching vibrational frequency. These criteria do not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The DeltaPA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length changes and the redshift favor the Z OH group, matching the results of NBO and AIM calculations. This reflects that the thermochemistry of adduct formation is not a good measure of the hydrogen bond strength in charged adducts, and that the ionic interactions in the E and Z adducts of protonated carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength.
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