Elucidating the Role of Electron-Donating Groups in Halogen Bonding

Abstract

Computational quantum chemical techniques were utilized to systematically examine how electron-donating groups affect the electronic and spectroscopic properties of halogen bond donors and their corresponding complexes. Unlike the majority of studies on halogen bonding, where electron-withdrawing groups are utilized, this work investigates the influence of electron-donating substituents within the halogen bond donors. Statistical analyses were performed on the descriptors of halogen bond donors in a prescribed set of archetype, halo-alkyne, halo-benzene, and haloethynyl benzene halogen bond systems. The σ-hole magnitude, binding and interaction energies, and the vibrational X•••N local force constant (where X = Cl, Br, I, and At) were found to correlate very well in a monotonic and linear manner with all other properties studied. In addition, enhanced halogen bonds were found when the systems contained electron-donating groups that could form intramolecular hydrogen bonds with the electronegative belt of the halogen atom and adjacent linker features.

A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

“…However, the inclusion of molecules containing At in this study provides an opportunity to expand the theoretical framework describing the structure, bonding, and reactivity of diarylhalonium compounds [ 27 ]. Although some relativistic effects of astatine may not be sufficiently incorporated in calculations [ 28 ], others have shown in theoretical and limited experimental studies that astatine does engage in halogen-bonding interactions [ 29 – 30 ]. In this work, a series of halogen-bond donor molecules and their halogen bond complexes with chloride anion were optimized at the M062x/6-311+G(d) level of theory [ 31 ] with def2-tzvpp used for iodine and astatine, and with SMD solvation in tetrahydrofuran (THF) incorporating Huber, Truhlar, and Cramer’s correction for bromine and iodine [ 32 ] using Gaussian 09 [ 33 ].…”