Quinoidal Azaacenes: 99 % Diradical Character
Sebastian N. Intorp, Manuel Hodecker, Matthias Müller, Olena Tverskoy, Marco Rosenkranz, Evgenia Dmitrieva, Alexey A. Popov, Frank Röminger, Jan Freudenberg, Andreas Dreuw, Uwe H. F. Bunz
Abstract
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 Δ E ST′ 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.
Topics & Concepts
DiradicalCharacter (mathematics)Electron paramagnetic resonanceParamagnetismSquidSpectroscopyChemistrySolid-stateCrystallographyPhotochemistryNuclear magnetic resonanceCondensed matter physicsAtomic physicsPhysical chemistryPhysicsQuantum mechanicsSinglet stateBiologyMathematicsGeometryExcited stateEcologySynthesis and Properties of Aromatic CompoundsFullerene Chemistry and ApplicationsSupramolecular Chemistry and Complexes