Most commonly, exploration of the minimum energy pathways (MEPs) on the potential energy surfaces (PESs) describing interactions between reacting molecules and the classical Arrhenius rate-equation, i.e. the transition state theory (TST), are thought to be sufficient for unraveling mechanisms of chemical reactions. Questions are, however, is TST/MEP approach sufficient for FLP reactions and does it provide sufficient guidance for experiment? To answer that, one has to examine actual movement of atoms as Lewis base/acid pairs, LB/LA for short, react with some other molecules. We present theoretical and computational aspects of first results indicating mechanistic consequence of the motion of atoms in reacting complexes of the type LB---X---LA, where LB and LA are encumbered (and thus heavy) Lewis base and Lewis acid while X is a relatively small (and thus light) molecule such as CO2 or H2. Also, we present the potential energy considerations which consistently account for the hierarchy of timescales uncovered by the direct ab initio molecular dynamics simulations (AIMD). To be presented are AIMD simulations showing new picture of FLP reactions because of (1) significant ratio of masses between the light reactant (X) and LB/LA counterparts; (2) flat potential surfaces E(LB---X---LA) as functions of LB---X and LA---X distances in chemically relevant saddle area; (3) coupling between the intrinsic reaction coordinate and the �internal� motion of X with respect to LB and LA in the reacting complexes; (4) effects arising from explicit solute-solvent interactions which tend to significantly slower the evolution of the LB/LA pair as �chemical environment�. In our contribution, details of AIMD simulations of CO2-binding by representative FLP will be presented.

Dynamical analysis of Frustrated Lewis acid/base chemistry: Unraveling the role of heavy-light-heavy molecular interactions characterized by flat potential energy surfaces

248th National Meeting (2014)

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