Correlation diagram approach as a tool for interpreting chemistry: an introductory overview

Abstract

In the frameworks of both molecular orbital (MO) and valence bond (VB) theories, the correlation diagram approach aids understanding of a wide range of chemical phenomena. MO-based correlation diagrams are based upon one-electron MOs or electronic configuration functions and have been broadly applied to both thermal and photochemical reactions. VB-based correlation diagrams utilize VB structures to express diabatic states and are especially powerful in analyzing chemical bonding and chemical reactivity. These approaches help us to understand the electronic behavior of molecules and fill the gap between intricate wave functions and the chemists' viewpoint. This paper provides an introductory overview of the correlation diagram approach, with a greater emphasis placed on VB state correlation diagrams.

An attempt to evaluate the effect of proton-coupled electron transfer on the H-abstraction step of the reaction between 1,1-dimethylhydrazine and cytochrome P450 compound I

“…To understand the electronic mechanism underlying the substrate-dependent reactivity differences in a chemical language, we performed an additional qualitative analysis using VB diagrams [34][35][36][37][38][39]. To describe each VB structure of a complex Cpd I system as concisely as possible, we shall employ the notation illustrated in Figure 4a (right).…”

Dihydropyrene/Cyclophanediene Photoswitching Mechanism Revisited with Spin-Flip Time-Dependent Density Functional Theory: Nature of the Photoisomerization Funnel at Stake!

“…Orbital and state correlation diagrams have long been used to provide an intuitive and qualitative picture of the isomerization mechanism in the ground and excited states of pericyclic reactions . Based on simple correlations between the molecular orbitals of the reactant and product along a symmetry-preserving reaction coordinate, valuable information on the topology of the ground- and excited-state potential energy surfaces can be obtained, in particular regarding the presence or not of potential energy barriers along the considered reaction coordinate in the respective electronic states. , The orbital and state correlation diagrams along the C 2 h symmetry-preserving cycloreversion coordinate of DHP into CPD are shown in Figure . The frontier orbitals of the DHP reactant (HOMO – 1: b g ; HOMO: a g ; LUMO: b u ; and LUMO + 1: a u ) are correlated with those of the CPD product (HOMO – 1: b g ; HOMO: b u ; LUMO: a g ; and LUMO + 1: a u ), showing a crossing of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels (Figure a).…”

Application of Hartree-Fock Method for Modeling of Bioactive Molecules Using SAR and QSPR

“…The reason for this is related to the fact that these properties provide information about the character electron donor and/or electron-acceptor and a compound thus forming a charge transfer complex (CTC) [92]. The energy of Highest Occupied Molecular Orbital Energy (HOMO) and Lowest Unoccupied Molecular Orbital Energy (LUMO) are quantum-chemical descriptors, which play an important role in chemical reactions and the formation of many complex charge transfer [93]. In Figure 4 is shown the fron- tiers orbital (HOMO and LUMO) with the respective values of energy (eV), using Hatree-Fock method at different basis sets (HF/3-21G*, HF/3-21G**, HF/6-31G, HF/6-31G*, HF/6-31G** and HF/6-311G) for aspirin, and this figure we note the delimited region for the HOMO orbital which measures the electron-donor character of aspirin, and the LUMO which measures the electron-acceptor character.…”