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Quinoidal Azaacenes: 99 % Diradical Character
Author(s) -
Intorp Sebastian N.,
Hodecker Manuel,
Müller Matthias,
Tverskoy Olena,
Rosenkranz Marco,
Dmitrieva Evgenia,
Popov Alexey A.,
Rominger Frank,
Freudenberg Jan,
Dreuw Andreas,
Bunz Uwe H. F.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201915977
Subject(s) - diradical , electron paramagnetic resonance , paramagnetism , character (mathematics) , chemistry , squid , spectroscopy , diamagnetism , solid state , crystallography , photochemistry , nuclear magnetic resonance , condensed matter physics , atomic physics , physics , singlet state , magnetic field , quantum mechanics , ecology , geometry , mathematics , biology , excited state
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.