Testing the nature of reaction coordinate describing interaction of H₂ with carbonyl carbon, activated by Lewis acid...

Using Born-Oppenheimer molecular dynamics (BOMD), we explore the nature of interactions between H₂ and the activated carbonyl carbon, C(carbonyl), of the acetone-B(C₆F₅)₃ adduct surrounded by an explicit solvent (1,4-dioxane). BOMD simulations at finite (non-zero) temperature with an explicit solvent produced long-lasting instances of significant vibrational perturbation of the H-H bond and H₂-polarization at C(carbonyl). As far as the characteristics of H₂ are concerned, the dynamical transient state approximates the transition-state of the heterolytic H₂-cleavage. The culprit is the concerted interactions of H₂ with C(carbonyl) and a number of Lewis basic solvent molecules-i.e., the concerted C(carbonyl)⋯H₂⋯solvent interactions. On one hand, the results presented herein complement the mechanistic insight gained from our recent transition-state calculations, reported separately from this article. But on the other hand, we now indicate that an idea of the sufficiency of just one simple reaction coordinate in solution-phase reactions can be too simplistic and misleading. This article goes in the footsteps of the rapidly strengthening approach of investigating molecular interactions in large molecular systems via "computational experimentation" employing, primarily, ab initio molecular dynamics describing reactants-interaction without constraints of the preordained reaction coordinate and/or foreknowledge of the sampling order parameters.