Singlet Open-Shell Character of Polyperiacenes - Graphene and Its Fascinating Attributes - page 51

2.4. More extended ring system
Using these findings, one can easily recognize open-shell electronic
structures in polyperiacenes of tetracene ( 4-B ; b = 3, 5, 7). All of these
compounds contain three or more sextets in the biradical structures in
comparison with the Kekulé structures, indicating a large contribution of
the biradical structures to the ground states. Unpaired electrons are prone
Fig. 5. NICS(1) values of polyacenes and polyperiacenes A-B .