Preprints
https://doi.org/10.5194/mr-2021-22
https://doi.org/10.5194/mr-2021-22

  24 Feb 2021

24 Feb 2021

Review status: a revised version of this preprint was accepted for the journal MR.

Non-classical disproportionation revealed by photo-CIDNP NMR

Jakob Wörner1, Jing Chen1, Adelbert Bacher2, and Stefan Weber1 Jakob Wörner et al.
  • 1Institute of Physical Chemistry, Albert-Ludwigs-Universität Freiburg, Freiburg, 79104, Germany
  • 2Department of Chemistry, Technical University of Munich, Garching, 85748, Germany

Abstract. Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron-reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, Aiso(H(6α)) and Aiso(H(8α)), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C–H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML) and neutral (TMLH) protonation forms.

Jakob Wörner et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on mr-2021-22', Anonymous Referee #1, 03 Mar 2021
  • RC2: 'Comment on mr-2021-22', Anonymous Referee #2, 25 Mar 2021
  • AC1: 'Author Comment on mr-2021-22', Stefan Weber, 31 Mar 2021

Jakob Wörner et al.

Jakob Wörner et al.

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