Determining the Factors accounting for Reaction Selectivity A Relative Energy Gradient - Interacting Quantum Atoms and Natural Bonding Orbitals Study

Abstract

Identifying the main physicochemical properties accounting for the course of a reaction is of utmost importance to rationalize chemical syntheses. To this aim, the relative energy gradient (REG) method is an appealing approach because it is an unbiased and automatic process to extract the most relevant pieces of energy information. Initially formulated within the interacting quantum atoms (IQA) framework for a single reaction, here we extend the REG method to natural bond orbitals (NBO) analysis and to the case of two competitive processes. This development enables the determination of the driving forces of any chemical selectivity. We illustrate the extended REG method on the case study of ring opening in cyclobutenes, which is an important instance of the so-called torquoselectivity.

Keywords: interacting quantum atoms; natural bonding orbitals; quantum theory of atoms-in-molecules; relative energy gradient; torquoselectivity.