Magnitude and Directionality of Halogen Bond of Benzene with C₆F₅X, C₆H₅X, and CF₃X (X = I, Br, Cl, and F)

Abstract

Geometries of benzene complexes with C6F5X, C6H5X, and CF3X (X is I, Br, Cl, and F) were optimized, and their interaction energies were evaluated. The CCSD(T) interaction energies at the basis set limit (Eint) of C6F5X (X is I, Br, Cl, and F) with benzene were -3.24, -2.88, -2.31, and -0.92 kcal mol(-1). Eint of C6H5X (X is I, Br, and Cl) with benzene were -2.31, -1.97, and -1.48 kcal mol(-1). The fluorination of halobenzenes slightly enhances the attraction. Eint of CF3X (X is I, Br, Cl, and F) with benzene (-3.11, -2.74, -2.22, and -0.71 kcal mol(-1)) were very close to Eint of corresponding C6F5X with benzene. In contrast to the halogen bond of iodine and bromine with pyridine (n-type halogen bond acceptor) where the main cause of the attraction is the electrostatic interactions, that of halogen bond with benzene (p-type acceptor) is dispersion interaction. In the halogen bonds with p-type acceptors (halogen-π interactions), the electrostatic interactions and induction interactions are small. The overall orbital-orbital interactions are repulsive. The directionality of halogen bonds with p-type acceptors is very weak, owing to the weak electrostatic interactions, in contrast to the strong directionality of the halogen bonds with n-type acceptors and hydrogen bonds.

Modeling halogen bonding with planewave density functional theory: Accuracy and challenges

“…On the basis of several popular energy decomposition frameworks, a number of recent studies pointed to the importance of dispersion interactions in the π-type XB interactions. [21,[38][39][40][41] Therefore, a straightforward low-cost remedy is to include Grimme's dispersion corrections in the optimization of AR-type XB dimers. It is clear from Table 3 that the inclusion of Grimme's D2 and D3 dispersion corrections to the PBE-PAW method (abbreviated as PBE-D2-PAW and PBE-D3-PAW, respectively) give excellent agreement to the MP2/cc-pVTZ XB lengths.…”

Separation of halogenated benzenes enabled by investigation of halogen–π interactions with carbon materials

“…The strength of the p interaction is considered to be determined by the induced dipole-dipole interaction or the induced dipole-induced dipole interaction. 33,[58][59][60][61][62] The potential energy of the induced dipole-dipole interaction is given as follows:…”

“…32 The importance of X-p interactions is now recognized, and many properties (magnitude directionality and origin of the X-p interaction) have been claried with high level computational methods based on theoretical chemistry. 33,34 Despite the progress, additional experimental data on X-p interactions are necessary because the halogen bond is in physical competition with many other stronger noncovalent interactions, including the hydrophobic interaction, hydrogen bond, and electrostatic interaction. [35][36][37] As a few reports, Nazaré et al indicated the experimental approach to reveal the strength of halogen-p interaction using bicyclic N-arylimide based molecular torsion balances system.…”

A Solvation/Desolvation Indicator Based on van der Waals Interactions between Solvents and Porphyrins

“…Reasons for thel ow solvation of fluorobenzenes (Nos. [22][23][24] are probably its relatively low polarizability comparedw ith that of other halobenzenes and the strong solvent-solvent interactions among the fluorobenzene molecules based on intermolecular HÀFhydrogen bonding.…”