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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. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 [ABSTRACT FROM AUTHOR]

Abstract: In this work, a systematic theoretical investigation on a series of dimeric complexes formed between MH2 and HX has been carried out by employing correlated ab initio methods. It was shown that besides dihydrogen bonds, there also exists novel noncovalent X⋯H interactions between the two molecules, which have similar characteristics to traditional halogen bonds. Upon complexation, the Hend to elongate in all cases, concomitant with red-shifts of the Hing frequencies. X⋯H interaction energies, calculated at the MP2/aug-cc-pvtz level, range from −2.11 to −11.78kJ/mol; the interactions are much weaker than corresponding dihydrogen bonds. The major stabilization source of dihydrogen and halogen bonds arises from the electrostatic force, while charge-transfer force plays a minor role in the formation of the complexes. AIM analyses further confirm the presence of X⋯H interactions in the systems, and the electron density at bond critical points correlates fairly well with the interaction energy. [Copyright &y& Elsevier]