One of the principle questions regarding the feasibility and the mechanism of chemical changes when molecules interact involves structures of transition states (TSs) which are theoretically defined as the first-order saddle points of potential energy surfaces (PESs). A central role assigned to TSs and the assumption that even at finite temperature reactions follow closely the minimum energy pathway (MEP) represented by the intrinsic reaction coordinate (IRC) may in fact be challenged by any combination of factors such as the topology of PESs itself, thermal non-equilibrium (non-statistical energy distributions), thermal kinetic and the internal energy of molecules as well as finite time scales of inter- and intra-molecular energy relaxation processes. With ab initio, molecular dynamics (AIMD) simulations we find out how the dynamics-driven donor-acceptor interactions define the reaction pathways of the reaction, B(C6F5)3 + P(tBu)3 + H2 ? (tBu)3PH(+)... H(-)B(C6F5)3,[1]at finite temperature (T=300 K). In our calculations the electronic structure of the whole molecular system and thus the energy and all the forces are re-computed at each time step of the simulation using an accurate level of the density functional theory with the dispersion correction (DFT-D3). We show that the results derived on the basis of the DFT calculations strictly within TS-theory have only limited bearing on the actual mechanism of the mentioned reaction - primarily because of the complicated topology of the multi-dimensional PES.[1] G. C. Welch, D. W. Stephan, J. Am. Chem. Soc., 129 , 1880 (2007).

Reactivity of the bimolecular FLPs from the point of view of dynamics at finite temperature

245th National Meeting (2013)

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