Author ORCID Identifier
Akhtam Amonov https://orcid.org/0000-0002-5248-0881
Steve Scheiner https://orcid.org/0000-0003-0793-0369
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This work is licensed under a Creative Commons Attribution 4.0 License.
The relationship between the strength of a halogen bond (XB) and various IR and NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place a Br or I atom on a phenyl ring; each is paired with a collection of N and O bases of varying electron donor power. The weakest of the XBs display a C–X bond contraction coupled with a blue shift in the associated frequency, whereas the reverse trends occur for the stronger bonds. The best correlations with the XB interaction energy are observed with the NMR shielding of the C atom directly bonded to X and the coupling constants involving the C–X bond and the C–H/F bond that lies ortho to the X substituent, but these correlations are not accurate enough for the quantitative assessment of energy. These correlations tend to improve as the Lewis acid becomes more potent, which makes for a wider range of XB strengths.
Amonov, A.; Scheiner, S. Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers. Molecules 2023, 28, 7520. https://doi.org/10.3390/molecules28227520