Condensed-to-bond dual descriptor for the analysis of electron density rearrangement in π-conjugated compounds

This study proposes the application of the bond dual descriptor, computed using finite difference approximation, to investigate the electron density reorganization in π-conjugated compounds upon nucleophilic/electrophilic attack. Compared to the traditional bond Fukui function analysis, this descriptor offers a simpler approach, reducing the complexity of potential rearrangement scenarios in half and simplifying the interpretation. A series of ethylene derivatives have been tested allowing to explain the activation of the double bond in ethylene derivatives, the rearrangement of the electron density and its reduction in activation energies. In addition, it is shown that it is possible to explain the reactivity on Michael acceptors, the rearrangement of cis-1,3,5-hexatriene to form 1,3-cyclohexadiene and the preference of C₆₀ to react through its [6,6] over [5,6] bonds. The bond dual descriptor complements the atomic dual descriptor, enabling a comprehensive analysis of the chemical reactivity of π-conjugated compounds.