HRgCN and HRgNC as halogen bond acceptors (Rg=Kr and Xe): A theoretical study upon strength and nature of halogen⋯nitrogen and halogen⋯carbon interactions

Halogen bond interaction, a noncovalent interaction between a halogen atom X in one molecule and a negative site in another, plays a vital role in fields as diverse as molecular biology, drug design and material science. In the present study, strength and characteristic of halogen bond interactions between CF3X and HRgY molecules are investigated, where X = F, Cl, Br, I; Y = CN, NC; Rg = Kr, Xe. Halogen bonding energies, calculated at the MP2/aug-cc-pVTZ, span from −0.4 to −9.0 kcal/mol. One of the most pronounced patterns is the relationship between interaction energies and halogens VS,max values: Higher VS,max (more positive σ-holes) result in complexes that are more strongly bound. According to energy decomposition analysis, attractive electrostatic and dispersion components make the major contribution to the halogen bond interaction energies. Increasing the size and positive nature of a halogen’s σ-holes remarkably enhances the electrostatic contribution of the halogen-bonding interaction.