Characterizing the interplay of 'σ-hole’ and ‘σ*' interactions in chalcogen bonding

Intermolecular non-covalent interactions, such as hydrogen, halogen and chalcogen bonds, are crucial in gas phase and condensed phase chemistry. Here we investigate and challenge the conflicting ‘σ-hole’ and ‘σ*’ paradigms commonly used for the description of chalcogen bonds. Using density functional theory with our absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) scheme, we explore the conformational and geometric space of a range of tellurophene-like systems. Our results show that while the s-hole description is adequate to predict the electrostatic component of chalcogen bonds, the additional contribution of charge transfer is needed to fully describe these interactions. We anticipate that our findings will offer fresh insight into the use of non-covalent interactions for crystal engineering, synthetic and biological chemistry.