In a recent article published in Angew. Chem. Int. Ed., 2016, 55, 9316-9320 (hot paper), (Link), Dr. Chi and her co-workers synthesized a series of extended bis(benzothia)-quinodimethanes and their dications as stable species. The neutral compounds mainly have a quinoidal structure in the ground state but show increased diradical character with extension of the central quinodimethane unit. More importantly, the dications exhibit similar electronic absorption spectra, NMR spectra, NICS values, and diatropic ring currents to their aromatic all-carbon acene analogues and thus can be regarded as genuine isoelectronic structures of pentacene, hexacene and heptacene, respectively. This study provides a new way to design and synthesize stable longer acene analogues with similar electronic structures to the traditional all-carbon acenes.
