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Dynamical Analysis of Chemical Activity of Sterically Encumbered Lewis acid/base Pairs
Stockholm University, Faculty of Science, Department of Organic Chemistry.
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This licentiate thesis is about the dynamics analysis of chemical reactions involving a stoichiometric mixture of sterically hindered Lewis base (LB) and Lewis acid (LA) – the so-called frustrated Lewis pairs (FLPs). The tool for dynamical description of chemical reactions is the ab initio molecular dynamics (AIMD) simulations together with the calculation of minimum energy paths (MEPs) on the potential energy surfaces (PESs). The aim is to take into account both the interatomic forces, computed with the dispersion-corrected density functional theory, and the motion of the atoms at finite (non-zero) temperature. With extensive AIMD/PES simulations, we have exposed and explained transition state theory (TST)/MEP paradigm failures for such important chemical reactions as binding (sequestration) of CO2 and the heterolytic cleavage of H2 by a Lewis base, tBu3P, and a Lewis acid, B(C6F5)3. The insight into dynamical aspects of FLP activity, obtained from a synergistic combination of AIMD and PES calculations, is the basis for qualitative and quantitative predictions which could be useful for future experiments

Abstract [sv]

Denna licentiatavhandling behandlar dynamisk analys av kemiska reaktioner som involverar en stökiometrisk blandning av steriskt hindrade Lewis-baser (LB) och Lewis-syror (LA) molekyler - så kallade frustrerade Lewis-par (FLP). Ett verktyg för dynamisk beskrivning av kemiska reaktioner är “ab initio molecular dynamics” (AIMD)-simuleringnar tillsammans med beräkningen av “minimal energy paths” (MEP) på “potential energy surfaces” (PES). Syftet är att ta hänsyn till både interatomära krafter och rörelsen hos atomerna vid ändliga temperaturer. Vi har kunnat visa att FLP-reaktioner (kemiska reaktioner som involverar LB/LA-par) inte sker enligt MEP på grund av att grundantaganden som gjorts i “transitition state theory” inte är uppfyllda. Exempel på analyserade kemiska reaktioner är fångandet av den primära växthusgasen CO2 och splittring av H2. Genom en synergistisk kombination av dynamiska analyser och PES-beräkningar, får vi en ny insikt i mekanismerna och kan därmed göra kvantitativa förutsägelser för framtida experiment.

Place, publisher, year, edition, pages
Stockholm: Stockholm University, 2014. , 49 p.
National Category
Organic Chemistry
URN: urn:nbn:se:su:diva-108096OAI: diva2:753925
2014-11-03, K439+K433, Arrhenus Lab., Stockholm University, 14:00 (English)
Knut and Alice Wallenberg Foundation
Available from: 2014-10-09 Created: 2014-10-09 Last updated: 2014-10-09Bibliographically approved

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Pu, Maoping
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Department of Organic Chemistry
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