Near Equivalence of Polarizability and Bond Order Flux Metrics for Describing Covalent Bond Rearrangements

TL;DR

This study demonstrates that bond flux metrics and polarizability measures are nearly equivalent in identifying covalent bond breaking points, offering a simpler and insightful approach for analyzing chemical reactions.

Contribution

It reveals the near equivalence of bond flux and polarizability metrics in detecting bond dissociation, providing a new, simpler method for studying covalent bond rearrangements.

Findings

Bond flux maximization aligns with polarizability maxima.

Wiberg-Mayer bond flux offers a simpler calculation method.

Applicable to various reactions including nitrogen bond breaking and hydrogen combustion.

Abstract

Identification of the breaking point for the chemical bond is essential for our understanding of chemical reactivity. The current consensus is that a point of maximal electron delocalization along the bonding axis separates the different bonding regimes of reactants and products. This maximum transition point has been investigated previously through the total position spread and the bond-parallel components of the static polarizability tensor for describing covalent bond breaking. In this paper, we report that the first-order change of the Wiberg and Mayer bond index with respect to the reaction coordinate, the bond flux, is similarly maximized and is nearly equivalent with the bond breaking points determined by the bond-parallel polarizability. We investigate the similarites and differences between the two bonding metrics for breaking the nitrogen triple bond, twisting around the ethene double bond, and a set of prototypical reactions in the hydrogen combustion reaction network. The Wiberg-Mayer bond flux provides a simpler approach to calculating the point of bond dissociation and formation and can yield greater chemical insight through bond specific information for certain reactions where multiple bond changes are operative.