Describing the Molecular Mechanism of Organic Reactions by Using Topological Analysis of Electronic Localization Function

Abstract

Here, we provide an essay on the analysis of the reaction mechanism at the molecular level; in particular, the evolution of the electron pair, as it is provided by the ELF, is used to decribe the reaction pathway. Then, the reaction mechanism is determined by the topological changes of the ELF gradient field along a series of structural stability domains. From this analysis, concepts such as bond breaking/forming processes, formation/annihilation of lone pairs and other electron pair rearrangements arise naturally along the reaction progress simply in terms of the different ways of pairing up the electrons. To visualize these results some organic reaction mechanisms (the thermal ring aperture of cyclobutene and cyclohexa-1,3-diene) have been selected, indicating both the generality and utility of this type of analysis.

Curly arrows meet electron density transfers in chemical reaction mechanisms: from electron localization function (ELF) analysis to valence-shell electron-pair repulsion (VSEPR) inspired interpretation

“…The potential applications of the method cover the determination of the mechanisms of reactions belonging to organic as well as inorganic chemistry as done in recent studies. 79,81,82,122,136,143,146,[167][168][169][170][171][172][173] We believe that the approach proposed here can thus be useful not only in a variety of circumstances to provide quantitative insights into the nature of chemical reactivity and for the modelling of reaction mechanism, based on the electron density transfers but also it should become a powerful tool in the chemical education of undergraduate students because our theoretical findings can serve as a general guideline for the study and analysis of the chemical structure and reaction mechanisms. Our understanding of the chemical structure and reactivity is usually built up from and dependent upon such intuitive concepts as atom in molecule, chemical bond, lone pair, Lewis structure, etc.…”

Chemical structure and reactivity by means of quantum chemical topology analysis

“…Thus, to further increase the applicability of the Thom´s CT in chemical systems Silvi et al [153] have developed the Bonding Evolution Theory (BET) as a generalization of Bader's work and to other scalar fields as ELF [153,154]. A number of reaction types have been investigated using BET including reactions of cycloaddition [155,156], cyclization [157][158][159], electron transfer [160], inversion substitution [161], electronic fluxes during Diels-Alder reactions [156], involving metal compounds [162][163][164][165] and inorganic reactions involving Mo complexes [166,167] while MoralesBayuelo has analyzed the electronic reorganization in the thermal isomerization reaction of trans-3,4-dimethylcyclobutene [168]. Nizovtsev [169] has also studied the activation of C-H bond in CH 4 by Pd atom as well as electronic rearrangements during the Inversion of Lead Phthalocyanine [170] from a BET perspective to establish electron density redistribution in the course of structural rearrangements.…”

“…Nizovtsev [169] has also studied the activation of C-H bond in CH 4 by Pd atom as well as electronic rearrangements during the Inversion of Lead Phthalocyanine [170] from a BET perspective to establish electron density redistribution in the course of structural rearrangements. Different examples where BET has been successfully applied to rationalize chemical reactivity have been reviewed comprehensively [155,158,171].…”

Inquiry of the electron density transfers in chemical reactions: a complete reaction path for the denitrogenation process of 2,3-diazabicyclo[2.2.1]hept-2-ene derivatives

“…[30][31][32][33][34][35][36][37][38][39][40][41]43,56,57 The topological partition of the ELF gradient field Along a reaction pathway (which links the chemical structures and therefore the topologies of the ELF gradient fields of the reactants with those of the products) the system experiences a series of structural stability domains (SSDs) within which all the critical points are hyperbolic separated by catastrophic points at which at least one critical point is non-hyperbolic. The bifurcation catastrophes occurring at these turning points are identified according to Thom …”

“…[30][31][32][33][34][35][36][37][38][39][40][41][42] To obtain a trustworthy picture, one must first perform computational studies, and then post-process the complicated information encoded in the accurate wave function in a way that facilitates chemical interpretation where concepts from QCT are used to provide insight into the molecular electronic structure and the changes in the electronic structure that accompany chemical processes. It is worth noting that an important feature of BET is the ability to observe the flow of the electron density as the reaction proceeds; in other words, BET allows the monitoring of a chemical rearrangement along the reaction coordinate.…”