From Local Topology to Molecular Geometries via Minimizing the Total Energy: The Pyrolysis of Cubane

This work gauges a recent methodical approach to elucidate an intimate multi-correlation between electron reorganizations, most stable molecular configurations, and the topographical description of relevant chemical processes through an in-depth reevaluation of the chemical bonding analysis underpinning the cubane pyrolysis mechanism reported by Seif et al. [RSC Adv., 2020, 10, 32730-32739]. Within the original version of the bonding evolution theory, both the single scissions and double formations/breakages of carbon-carbon bonds featuring the elementary reactions of such a mechanism were mischaracterized in terms of the cusp unfolding. However, no flag of this polynomial was detected in the first step (i.e., cubane bicyclo[4.2.0]octa-2,4,7-triene) as evidenced by the determinant of the Hessian matrix at all potentially degenerate critical points of the electron localization function along the intrinsic reaction coordinate. The crucial transannular ring opening featuring the second reaction, bicyclo[4.2.0]octa-2,4,7-triene 1,3,5,7-cyclooctatetraene, is the only chemical process exhibiting cusp characteristics. This striking finding underscores the significance of the density symmetry’s persistency near the topographical bifurcation, which serves as a predictive tool for correctly assigning the unfoldings characterizing key chemical changes along a pathway, a priori, i.e., by visually inspecting the molecular geometry. Our results reveal that both functions constitute a sophisticated model for assessing the electronegativity in reacting systems as they give an image of bonds’ polarity that consistently aligns with chemists’ expectations. The computed thermochemical dataset closely matches the experimental values, demonstrating the robustness and accuracy of the derived insights.