Distinguishing Bonds

Abstract

The energy change per electron in a chemical or physical transformation, ΔE/n, may be expressed as Δχ̅ + Δ(VNN + ω)/n, where Δχ̅ is the average electron binding energy, a generalized electronegativity, ΔVNN is the change in nuclear repulsions, and Δω is the change in multielectron interactions in the process considered. The last term can be obtained by the difference from experimental or theoretical estimates of the first terms. Previously obtained consequences of this energy partitioning are extended here to a different analysis of bonding in a great variety of diatomics, including more or less polar ones. Arguments are presented for associating the average change in electron binding energy with covalence, and the change in multielectron interactions with electron transfer, either to, out, or within a molecule. A new descriptor Q, essentially the scaled difference between the Δχ̅ and Δ(VNN + ω)/n terms, when plotted versus the bond energy, separates nicely a wide variety of bonding types, covalent, covalent but more correlated, polar and increasingly ionic, metallogenic, electrostatic, charge-shift bonds, and dispersion interactions. Also, Q itself shows a set of interesting relations with the correlation energy of a bond.

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

“…They could be viewed as having varying degrees of “dative” or “coordinate covalent” character. The gradation in interaction energies that is observed is in accord with the concept that chemical bonding is a continuum of forms, ranging from weak to strong …”

“…The gradation in interaction energies that is observed is in accord with the concept that chemical bonding is a continuum of forms, ranging from weak to strong. [32,103,[110][111][112][113] Finally, we want to point out that the value of the electrostatics/polarization relationships that have been discussed is primarily conceptual rather than predictive. They serve the very important purpose of providing strong support for the Coulombic description of σand π-hole interactions.…”

Signatures of van der Waals binding: A coupling-constant scaling analysis

“…One can generally sort chemical bonds from knowledge of the average orbital energy. 78 The average orbital energy is a measure that will, in principle, reflect all correlation effects, including those that are manifested in the kinetic energy.…”

A Variety of Bond Analysis Methods, One Answer? An Investigation of the Element−Oxygen Bond of Hydroxides HnXOH

“…In a very recent method, here referred to as the Q‐analysis, developed by Rahm and Hoffmann, energetic contributions to bonding are evaluated in a different way . According to this approach, the energy change per electron upon bonding, , may be expressed as , where is the change in the average binding energy, Δ V NN is the change in the nuclear repulsion, and Δ ω is the change in multielectron interactions (such as the electron repulsion and exchange‐correlation energies) referring to a homolytic bond formation (A .…”