Experimental Evidence for Non-Fermi-Contact J Coupling Across Chalcogen Bonds in Ionic Salt Cocrystal Polymorphs

Tamali Nag; Victor V Terskikh; David L Bryce

doi:10.1002/anie.202402441

Experimental Evidence for Non-Fermi-Contact J Coupling Across Chalcogen Bonds in Ionic Salt Cocrystal Polymorphs

Angew Chem Int Ed Engl. 2024 May 21;63(21):e202402441. doi: 10.1002/anie.202402441. Epub 2024 Apr 11.

Authors

Tamali Nag¹, Victor V Terskikh², David L Bryce¹

Affiliations

¹ Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada, K1H 5H5.
² Metrology, National Research Council Canada, Ottawa, Ontario, Canada, K1A 0R6.

PMID: 38498337
DOI: 10.1002/anie.202402441

Abstract

A pair of novel polymorphic ionic cocrystals of 3,4-dicyanotelluradiazole and tetraphenylphosphonium bromide are synthesized and are characterized by single-crystal XRD. Strong and directional non-covalent chalcogen bonds (ChB) between Te and Br are analyzed via solid-state NMR to reveal large and anisotropic J(¹²⁵Te,^79/81Br) coupling tensors, providing unequivocal evidence for non-Fermi contact contributions across ChBs. Along with large ^79/81Br quadrupolar couplings for the Br^- anions, these data provide new tools to characterize chalcogen bonds and to differentiate between ChB polymorphs.

Keywords: NMR spectroscopy; chalcogen bond; coupling constant; crystal engineering; indirect nuclear spin-spin coupling; non-covalent interaction; polymorphism; solid-state NMR; tellurium.

Grants and funding

Natural Sciences and Engineering Research Council of Canada