Abstract
Chalcogen bonding is a non-covalent interaction gaining increasing interest in various fields including materials science and biochemistry. Although chalcogen bonding in the solid state is commonly characterised using NMR and X-ray crystallography, complementary techniques are needed to fully understand the solid-state behaviour of this interaction in order to establish robust structure-property relationships. This work presents the synchrotron far infrared spectra of five chalcogen bonding co-crystal systems comprising ebselen derived chalcogen bond donors with the Lewis base, DMAP. The experimental results are in good agreement with calculated periodic DFT vibrational modes at the B3LYP-D3/def2-SVP level.Crystalline powder samples show strong signals between 60-115 cm-1 , which upon visualisation of the calculated eigenvectors, were confidently assigned to chalcogen bonding vibrations. Ultimately, this work represents, to our knowledge, one of the first uses of far-infrared spectroscopy to identify chalcogen bonding interactions in solid-state crystalline systems.