Halogen bonding. The role of the polarizability of the electron-pair donor

Abstract

The nature of F-BrX-R interactions (with X = F, Cl, Br, I and R = -H, -F) has been investigated through theoretical calculation of molecular potential electrostatic (MEP), molecular polarizability, atoms in molecules (AIM) analysis and energetic decomposition analysis (EDA). A detailed analysis of the MEPs reveals that considering only the static electrostatic interactions is not sufficient to explain the nature of these interactions. The molecular polarizabilities of X-R molecules suggest that the deformation capacity of the electronic cloud of the lone pairs of the X atom plays an important role in the stability of these complexes. The topological analysis of the L(r) = -¼∇(2)ρ(r) function and the detailed analysis of the atomic quadrupole moments reveal that the BrX interactions are electrostatic in nature. The electron acceptor Br atom causes a polarization of the electronic cloud (electronic induction) on the valence shell of the X atom. Finally, the electrostatic forces and charge transfer play an important role not only in the stabilization of the complex, but also in the determination of the molecular geometry of equilibrium. The dispersive and polarization forces do not influence the equilibrium molecular geometry.

In Silico Modeling of Indigo and Tyrian Purple Single-Electron Nano-Transistors Using Density Functional Theory Approach

“…5b). Since, the polarizability of a halogen atom increases in the order of F < Cl < Br, bromine shows large polarizability between the halogen atoms [30]. These data also reflected the experimentally determined relative permittivity values of 4.3 for indigo and 6.2 for Tyrian purple calculated from the geometric capacitance at high frequency (>1.0 MHz) [4].…”

Electronic and Steric Manipulation of the Preagostic Interaction in Isoquinoline Complexes of RhI

“…Turning to the atomic‐basin properties for 1 (Table ), the H‐ and Rh‐atomic charges are both positive [ q (H) and q (Rh) values are 0.053 e and 0.604 e , respectively] which would provide the basis for weak repulsion. Examination of the Laplacian of the electron density, ∇ 2 ϱ , indicates that there are no complicating factors due to dipolar or higher‐order multipolar interactions from anisotropic charge accumulations that could affect the interpretation as being anything other than repulsive in nature. The weak repulsion could also be the basis for the small C–H bond deformation away from the aromatic‐ring plane (–1.2°) that is associated with the interaction.…”

Electrostatics and Polarization in σ‐ and π‐Hole Noncovalent Interactions: An Overview

“…Electrostatics alone is never sufficient to describe with full accuracy an intermolecular interaction; polarization must be taken into account. This was recognized by Scrocco and Tomasi, who pioneered the analysis of molecular electrostatic potentials, and it has been pointed out and discussed in detail numerous times since then . Nevertheless, the insufficiency of electrostatics alone continues to be “rediscovered” and cited, incorrectly, as indicating the inadequacy of σ‐ and π‐hole interpretations of noncovalent interactions.…”

“…Thus the V( r ) computed for the free molecules gradually become somewhat less meaningful as the molecules approach each other. Polarization is an intrinsic, stabilizing part of a Coulombic interaction, along with electrostatics . The degree to which each molecule undergoes polarization depends upon its polarizability and upon the strength of the electric field to which it is subjected.…”