In Situ Electronegativity and the Bridging of Chemical Bonding Concepts

This article was originally published here

Chemistry. 2021 Oct 20. doi: 10.1002/chem.202103477. Online ahead of print.

ABSTRACT

A challenge in chemistry is the plethora of often disparate models for rationalizing the electronic structure of molecules. Chemical concepts abound, but their connections are often frail. This work describes a quantum mechanical framework that enables a combination of ideas from three approaches common for the analysis of chemical bonds: Energy Decomposition Analysis (EDA), Quantum Chemical Topology, and Molecular Orbital (MO) Theory. The glue to our theory is the electron energy density, interpretable as one-part electrons and one-part electronegativity. We present a three-dimensional analysis of the electron energy density and use it to redefine what constitutes an atom in a molecule. Definitions of atomic partial charge and electronegativity follow in a way that connects these concepts to the total energy of a molecule. Formation of polar bonds are predicted to cause inversions of electronegativity and a new perspective of bonding in diborane and guanine-cytosine base-pairing is presented. Electronegativity of atoms inside molecules is shown to be predictive of pKa.

PMID:34668618 | DOI:10.1002/chem.202103477