Freiburg 2024 – wissenschaftliches Programm

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SYCC: Symposium Controlled Molecular Collisions

SYCC 1: Controlled Molecular Collisions

SYCC 1.1: Hauptvortrag

Mittwoch, 13. März 2024, 11:00–11:30, Paulussaal

Dynamics of CO₂ activation by transition metal ions - The importance of intersystem crossing — •Jennifer Meyer — Fachbereich Chemie und Forschungszentrum OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserlautern, Germany

Understanding chemistry at the level of a reactive collision, that is how atoms rearrange during the reactive event, is a fundamental question for physics and chemistry. The energetics along the reaction coordinate are important and the influence of barriers is often used to predict the outcome of a reaction. However, in small systems, especially in gas phase, submerged barriers with respect to reactants can exert a profound influence.

Here, we present a joint experimental and theoretical study on the possible effects of intersystem crossing on the dynamics of transition metal ion-molecule reactions and determine the nature of the bottleneck for Ta⁺ + CO₂. Recent crossed beam imaging experiments in our group on the dynamics on oxygen atom transfer (OAT) reaction Ta⁺ + CO₂ → TaO+ + CO showed dominantly indirect dynamics despite the thermal rates being close to collision rate and the reaction being highly exothermic. The question to the nature of the bottleneck along the reaction coordinate arose: a submerged transition state or the intersystem crossing. A combination of differential cross sections, thermal rate constants and high level theory for the OAT for Ta⁺ and its lighter homologue niobium Nb⁺ could shed some more light on the question.

Keywords: crossed beam; velocity map imaging; ion molecule reaction dynamics; transition metal; CO2 activation