Supramolecular covalency of halogen bonds revealed by NMR contact shifts in paramagnetic cocrystals
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Article in Periodical |
| Magazine / Source | Chemical Science |
| MU Faculty or unit | |
| Citation | |
| web | DOI: 10.1039/D5SC05769H |
| Doi | https://doi.org/10.1039/D5SC05769H |
| Keywords | chemical bond; NMR spectroscopy; DFT calculation; paramagnetic; hyperfine shift; |
| Attached files | |
| Description | Although supramolecular interactions such as halogen bonding are often classified as “non-covalent” interactions, computational methods have predicted that they possess a significant covalent component. In this article, we adopt a unique strategy that combines experimental solid-state NMR and relativistic DFT approaches to explore the electronic nature of previously postulated supramolecular covalency. Our approach involves the analysis of hyperfine interactions and hyperfine shifts in the NMR spectra of halogen-bonded cocrystals containing a paramagnetic transition-metal complex. We demonstrate that the hyperfine interaction pertaining to the paramagnetic transition-metal center and observed at the probed nucleus of the cocrystallized (halogen-bonded) molecule is governed by the Fermi-contact mechanism. This contact mechanism originates in “through-bond” spin transmission and, therefore, unequivocally reports on the electron sharing between the halogen-bonded molecules, i.e., halogen-bond covalency. |
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