Correlation between Equilibrium Constant and Stabilization Energy: A Combined Approach Based on Chemical Thermodynamics, Statistical Thermodynamics, and Density Functional Reactivity Theory

Abstract

In the present work, an attempt is made to establish the correlation between equilibrium constant and stabilization energy [ΔE SE(AB)] generated from density functional reactivity theory (DFRT). The reactions chosen here are of type A + B ⇌ AB (i.e., adduct formation type) between an electron acceptor, A, and an electron donor, B. The representative acceptors are methyltrioxorhenium (MTO) and substituted benzaldehydes whereas donors are 26 mono- and bidentate ligands (having N-donors) and semicarbazide. The trends of experimentally generated equilibrium constant (K) values match with those of ΔE SE(AB) in most of the cases, both in gas phase as well as in solvent. Justification of this reliable correlation is provided analytically using the expressions of standard Gibbs free energy of reaction (i.e., Δ r G θ) and the stabilization energy expression generated by DFRT. A further analytical explanation (albeit not very rigorous) is provided through statistical thermodynamics showing how equilibrium constant (K) is related to ΔE SE(AB) for reactions of the type A + B ⇌ AB, where either A or B is a common species.

DFT Computational Studies on Some Cobaloximes

“…Density functional reactivity theory is a powerful tool in studying the properties of molecules and interactions between two drug-target species (Sarmah and Roy, 2013;Sarmah and Roy, 2014). It can be also used to predict, analyze and interpret the outcome of chemical reactions (Bagaria et al, 2009;Saha et al, 2019;Roy, 2020 Hamid andRoy, 2020;Frau et al, 2017). In previous theoretical studies on some cobaloximes, their molecular properties and hydrogen-producing mechanisms (Solis and Hammes-Schiffer, 2011;Bhattacharjee and Andreiadis, 2013;Muckerman and Fujita, 2011;Solis et al, 2013;Jiang and Liu, 2012) were investigated using DFRT.…”

Validation of Hammett’s Linear Free Energy Relationship Through an Unconventional Approach

“…Incidentally, the “net desolvation energy” turned out to be the “negative of free energy of solvation” . Recently, Hamid and Roy have developed a relation between equilibrium constant ( K ) and density functional reactivity theory (DFRT)-based stabilization energy for a related series of reactions.…”