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Using the reaction electronic flux, a new tool aimed at identifying and characterizing the electronic activity taking place during a chemical process, the chelotropic and cycloaddition reactions of 1,3-butadiene with sulfur dioxide are revisited. The mechanisms of both reactions were studied within the framework of the reaction force analysis; the electronic activity determined through the reaction electronic flux was rationalized in terms of chemical events, bond forming or breaking processes, and polarization and transfer effects localized on the reactants species. The results show interesting features and differences between both the mechanisms; while the chelotropic path is driven by through space electrostatic interactions, the cycloaddition reaction is mainly driven by through bond electronic activity. The relation between these findings and the experimentally found kinetic (cycloaddition) and thermodynamic (chelotropic reaction) control is discussed. Int J Quantum Chem, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In our continuous effort to retrieve the Woodward-Hoffmann rules from conceptual density functional theory (DFT), we have examined the last type of pericyclic reactions, i.e., chelotropic reactions. Both the initial hardness response and the dual descriptor have been investigated to predict the allowed and forbidden character for the addition of SO2 to butadiene {An system) and 1,3,5-hexatriene {An + 2 system). It is shown that with both electronic descriptors, the conrota- tory/disrotatory mode for the linear and nonlinear mechanisms are retrieved based on a density-only approach, free from consideration of orbital and (or) wave function symmetry. The dual descriptor moreover reveals that stabilizing interactions are presented only for the linear path, which can be considered as an overall favourable mechanism for a chelotropic reaction. [ABSTRACT FROM AUTHOR]

Abstract: Nucleophilicity and elecrophilicity of mono and disubstituted silylenes are analyzed using the molecular electrostatic potential and the dual descriptor , defined within the so called conceptual DFT. A set of 32 compounds has been chosen which can be classified into 4 groups or families based on a linear relationship between the molecular electrostatic potential measured in the electrophilic (empty 3 orbital) and nucleophilic (lone pair) regions around of the silicon atom. The electrophilic and nucleophilic character of silylenes given by is connected to the orbital-resolved dual descriptor through the -electron donating property of the substituent. [Copyright &y& Elsevier]

Abstract: A theoretical study of the conformational dependence of energy and electronic properties of neutral and protonated histamine tautomers was performed with the aim of modelling its interaction with an hypothetical receptor. Analysis of chemical potential, electrophilicity, dipole moment, at the global level, as well as the dual descriptor por chemical reactivity, at local level, indicate that the π tautomer presents the right conformation and reactivity behavior to interact with the receptor. [Copyright &y& Elsevier]