Cubane Pyrolysis: Scaling Bond Polarity with Universal Polynomials

Abstract

This study presents a novel methodological approach to elucidate the intricate multi-correlation between electron reorganizations, the most stable molecular configurations, and the topographical description of relevant chemical processes. In such a context, an in-depth reevaluation of the chemical bonding analysis underpinning the cubane pyrolysis mechanism, as reported by Seif et al. [RSC Adv., 2020, 10, 32730-32739] is achieved. A fold-cusp unified model of universal functions for scaling bond polarity is derived from this multi-nexus. The scaling revealed that bond polarity index values within the interval [0, 10-5] au correspond to the cusp unfolding, while the fold spans over a wider interval, [10-3, ∞) au. Contrary to previous observations, no cusp flag was detected upon re-examining single scissions and double formations/breakages of carbon-carbon bonds in the first step of the reaction mechanism (i.e., cubane to bicyclo[4.2.0]octa-2,4,7-triene), as demonstrated by the determinant of the Hessian matrix at all potentially degenerate critical points of the electron localization function along the intrinsic reaction coordinate. The transannular ring opening in the second elementary reaction (bicyclo[4.2.0]octa-2,4,7-triene to 1,3,5,7-cyclooctatetraene) is the only chemical process exhibiting cusp characteristics, underscoring the model’s reliability. The computed thermochemical dataset closely matches the experimental values, highlighting the robustness and accuracy of the derived insights.