Correlation and Prediction of Redox Potentials of Hydrogen Evolution Mononuclear Cobalt Catalysts via Molecular Electrostatic Potential: A DFT Study

Abstract

Reduction potentials (E(0)) of six mononuclear cobalt catalysts (1-6) for hydrogen evolution reaction and electron donating/withdrawing effect of nine X-substituents on their macrocyclic ligand are reported at solvation effect-included B3P86/6-311+G** level of density functional theory. The electrostatic potential at the Co nucleus (V(Co)) is found to be a powerful descriptor of the electronic effect experienced by Co from the ligand environment. The V(Co) values vary substantially with respect to the nature of macrocycle, type of apical ligands, nature of substituent and oxidation state of the metal center. Most importantly, V(Co) values of both the oxidized and reduced states of all the six complexes show strong linear correlation with E(0). The correlation plots between V(Co) and E(0) provide an easy-to-interpret graphical interpretation and quantification of the effect of ligand environment on the reduction potential. Further, on the basis of a correlation between the relative V(Co) and relative E(0) values of a catalyst with respect to the CF3-substituted reference system, the E(0) of any X-substituted 1-6 complexes is predicted.

Ligand‐Based PCET Reduction in a Heteroleptic Ni(bpy)(dithiolene) Electrocatalyst Giving Rise to Higher Metal Basicity Required for Hydrogen Evolution

“…The use of B3P86/6‐31+G(d,p) level of DFT shows good consistency with theoretical and experimental results (see Figure S22 and Table S1), as described elsewhere ,. The redox potentials were calculated by employing the experimentally determined reduction potentials of Ni II (bpy)(qdt) (Figure S23) as the benchmark (see Scheme S1 for detail) ,. Moreover, the p K a DMF value of acetic acid (p K a DMF =13.5) was adopted as the benchmark to calculate the p K a values of the possible intermediates (see also Scheme S1 for detail) ,,…”

Electronic effect of β‐diketonato ligands on the redox potential of fac and mer tris(β‐diketonato) iron(III) complexes: A density functional theory study and molecular electrostatic potential analysis

“…MESP analysis is a good descriptor to determine the reactivity and stabilities of chemical and biological molecules . One of the important applications is using the MESP parameters (such as the MESP of an atom [ V atom or V Fe ], the minimum from the topological analysis of MESP iso‐surface [ V min ] and the maximum from the topological analysis of MESP iso‐surface [ V max ]) in determining the total electronic effect of ligands (eeL) on the molecule, in order to predict the reduction potential of molecules …”

“…The MESP analysis is an important method that has been used to understand several chemical phenomena, such as intermolecular interactions, and various chemical properties, such as bonding, chemical reactivity, inductive effect, and resonance. In addition to the application of MESP analysis to study various chemical properties, it has also been used to predict the reduction potential of compounds …”

Approach to the Mechanism of Hydrogen Evolution Electrocatalyzed by a Model Co Clathrochelate: A Theoretical Study by Density Functional Theory

“…In acidic media, platinum is the most efficient catalyst of the hydrogen evolution reaction (HER) but because of its scarcity and high sensitivity to trace amounts of pollutants, catalysts based on abundant and cheap metals are required. Several candidates have been investigated from experimental and theoretical points of view . The ultimate goal being to include such catalysts into systems that can transform visible light into useful chemical fuels .…”