The Nature and Magnitude of Specific Halogen Bonds Between Iodo-perfluorobenzene and Heterocyclic Systems

In this work, first-principle calculations at different levels of theory have been carried out to investigate a series of complexes formed between iodo-perfluorobenzene and several heteroatomic rings. Such model systems are selected to mimic halogen bonding interactions experimentally found within supramolecular architectures. In all cases, the predicted intermolecular distances are significantly shorter than the sums of van der Waals radii of I and N (O or S) atoms and the interactions appear to be highly directional. Halogen bonding energies, calculated at the MP2/lan12dz level, are substantial, ranging from -2.50 to -7.53 kcal/mol. Given the strength as well as the directionality comparable to hydrogen bonds, these synthons should be of general use in many fields of chemistry. Finally, to gain more insights into the nature of such interactions, we have used the natural bond orbital and atoms in molecules analyses on the studied systems, which show a considerable magnitude of charge transfer, significant orbital interaction, and distinct bond critical points between the two interacting atoms. (C) 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111: 2352-2358, 2011