Reaction path bifurcations and non-statistical dynamic effects - when do they occur, which methods are there to predict them, what modulates the product selectivity in such cases?
These are our guiding questions, that we follow in various projects that have carbo cations and radical cations as central intermediates.
NHC-stabilized radical centers
When we first identified NHC-stabilized radical centers in the bezoin reaction, we used that observation as a lead to find out more about the unqiue ability of NHCs to stabilize open-shell structures.
Within the CRC 325 we will widen this topic to the NHC-borane complexes and see where the journey will take us.
We use EPR-spectroscopy, KIEs and computations to unravel the mechanistic details. For light-triggered processes we have our own, irradiation unit for our BRUKER EPR and a ns-UV-pump-probe set-up for studying transients.
Transition metal catalysis
In recent years recognized as a potent method, despite the fact of the extremly short excited state lifetime of Cu-complexes.
Our mechanistic interest is mainly focussing on the part after the super fast photophysical processes have happened, i.e. in detail to when and how the (organic) radical formation takes place (inner vs. outersphere). These mechanisitc studies are complementing by the synthetic method development by Prof. Oliver Reiser's group.
For this project we use computational chemistry in combination with EPR featuring an irradiation unit.
Pd-catalysed oxidative Heck-couplings
Here we continue to rationalize the experimental observations of different product forming pathways that are opened or closed by rather subtle changes of the substrate.
The evaulation is done by in depth computational chemistry to rationaliz the experimental results obtained by the group of Prof. Oliver Reiser.
* computational and EPR-spectroscopic mechanistic studies on the light-induced Se-chemistry with the group of Prof. Alexander Breder (UR)
* computational mechanistic studies on photocatalytic transformations with the group of Prof. Malte Brasholz (University Rostock)
* computational mechanistic studies on interesting deviations of chemical reactivity in
hypervalent iodine chemistry with the group of Prof. Tanja Gulder (University Leipzig)
pericyclic reactions with the group of Prof. Oliver Reiser (UR)
* pump-probe exeperiments to identify key-intermediates in photocatalyzed or photochemical reactions with the groups
of Burkhard Koenig (UR)of Arwen Pearson (UHH/CFEL)