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Ensing Bernd

Visiting Senior Researcher
Theory and Simulation



  • Hydrogen Activation by Frustrated Lewis Pairs Revisited by Metadynamics Simulations

    Liu L., Lukose B., Ensing B. Journal of Physical Chemistry C; 121 (4): 2046 - 2051. 2017. 10.1021/acs.jpcc.6b09991. IF: 4.536

    Frustrated Lewis pairs have great potential as metal-free catalysts, for example, for the activation of molecular hydrogen. However, rational design of improved catalysts is hampered because the catalytic reaction mechanisms still remain largely unclear. In this study, we present a density-functional-theory-based metadynamics study of the hydrogen activation by a typical frustrated Lewis pair, tBu3P/B(C6F5)3. The computed free-energy landscape reveals a different reaction path compared with the ones in the literature. Importantly, we found different roles of the Lewis acid and base centers in the hydrogen activation. The rate-determining step is the hydride transfer to the Lewis acid, and the overall reaction is found to be exothermic once the proton transfer to the Lewis base step is accomplished. © 2017 American Chemical Society.


  • Reactive trajectories of the Ru2+/3+ self-exchange reaction and the connection to Marcus' theory

    Tiwari A., Ensing B. Faraday Discussions; 195: 291 - 310. 2016. 10.1039/c6fd00132g.

    Outer sphere electron transfer between two ions in aqueous solution is a rare event on the time scale of first principles molecular dynamics simulations. We have used transition path sampling to generate an ensemble of reactive trajectories of the self-exchange reaction between a pair of Ru2+ and Ru3+ ions in water. To distinguish between the reactant and product states, we use as an order parameter the position of the maximally localised Wannier center associated with the transferring electron. This allows us to align the trajectories with respect to the moment of barrier crossing and compute statistical averages over the path ensemble. We compare our order parameter with two typical reaction coordinates used in applications of Marcus theory of electron transfer: the vertical gap energy and the solvent electrostatic potential at the ions. © The Royal Society of Chemistry 2016.