How does the global electron density transfer diminish activation energies in polar cycloaddition reactions? A Molecular Electron Density Theory study

The key role of the Global Electron Density Transfer (GEDT) in polar cycloaddition reactions is analysed within the Molecular Electron Density Theory (MEDT) using Density Functional Theory (DFT) calculations at the MPWB1K/6-311G(d) computational level. A comparative MEDT study of the non-polar Diels-Alder reaction between cyclopentadiene (Cp) and ethylene and the polar Diels-Alder reaction between Cp and tetracyanoethylene makes it possible to establish that the GEDT taking place in the direction of the transition state structures favours the bonding changes required for the formation of the new C[sbnd]C single bonds along polar cycloaddition reactions. Analysis of the reactivity indices defined within the conceptual DFT at the ground state of the reagents makes it possible to predict the reactivity of organic molecules in polar reactions.