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Quinoidal Azaacenes: 99 % Diradical Character |
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| Authors: | Dr Sebastian N Intorp Manuel Hodecker Matthias Müller Olena Tverskoy Marco Rosenkranz Dr Evgenia Dmitrieva Dr Alexey A Popov Dr Frank Rominger Dr Jan Freudenberg Prof Andreas Dreuw Prof Dr Uwe H F Bunz |
| Institution: | 1. Organisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany;2. Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Ruprecht Karls-Universität Heidelberg, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany;3. Center of Spectroelectrochemistry, Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstraße 20, 01069 Dresden, Germany |
| Abstract: | Quinoidal azaacenes with almost pure diradical character (y=0.95 to y=0.99) were synthesized. All compounds exhibit paramagnetic behavior investigated by EPR and NMR spectroscopy, and SQUID measurements, revealing thermally populated triplet states with an extremely low-energy gap ΔEST′ of 0.58 to 1.0 kcal mol−1. The species are persistent in solution (half-life≈14–21 h) and in the solid state they are stable for weeks. |
| Keywords: | acenes heteroaromatics radicals structure elucidation synthetic methods |