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MO: Fachverband Molekülphysik
MO 8: MO Poster 2
MO 8.6: Poster
Dienstag, 10. März 2020, 17:00–19:00, Empore Lichthof
Investigation of the Nitrogen Release Mechanism of a Carbenonitrene Precursor — •Niklas Gessner1, Julien Rowen2, Wolfram Sander2, and Patrick Nuernberger1 — 1Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg — 2Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, 44780 Bochum
Carbenes and the closely related nitrenes are classes of highly reactive molecules. They are commonly generated by photolysis of a diazo or an azido functional group, respectively, releasing molecular nitrogen (N2). This process is well understood e.g. for the carbene 9-fluorenylidene [1] or the nitrene 2-fluorenylnitrene [2] that are both long-lived. However, the release mechanism of the carbenonitrene 2-nitreno-9-fluorenylidene (NFl) is still unknown due to the fact that its precursor needs to release in total two molecules of N2. This leads to the question whether photochemically, the diazo-nitrene or the azido-carbene is generated first and what happens in subsequent processes.
To address this issue, the generation of NFl in the aprotic solvent acetonitrile has been studied with ultrafast transient absorption spectroscopy. Indications for both a carbene and a nitrene intermediate are found on a picosecond time scale. These transient species can eventually lead to the formation of a carbenonitrene with a quintet ground state, as we identified in separate studies where the compounds are embedded in cryogenic rare-gas matrices.
[1] J. Wang et al., J. Am. Chem. Soc. 129, 13683-13690 (2007).
[2] J. Wang et al., Org. Lett. 25, 5211-5214 (2007).