We report the synthesis, structural characterisation, and optoelectronic properties of a highly electron deficient bi(cyclopropylidene)-framework (CN8CP2). The developed one-pot synthesis gives access to the dianionic species via thermally induced homocoupling of an iodinated precursor. The controlled oxidation yields the radical anion, and the neutral molecule can be electrochemically generated in situ. Single-crystal X ray diffraction studies of the dianion reveal molecular layers separated by counter ions, thereby enabling fluorescence in the solid-state. The structure of the radical anion reveals a highly ordered arrangement of π-stacked molecules. Optical spectroscopy and quantum chemical calculations indicate that the vibronic fine structure is governed by the vibrational modes of the cyclopropane core. The analysis of the electronic structures confirms extensive spin delocalisation for the radical anion and a pronounced σ aromaticity. The exceptional low energy levels of the acceptor orbitals are determined to −5.66 eV for the radical anion and −6.18 eV for the neutral species. Consequently, charge transfer to the neutral molecule or the radical anion results in the formation of the closed-shell dianion what circumvents instabilities that are associated with open-shell species formed for conventional electron acceptors. Thus, CN8CP2 appears as one of the strongest small molecule organic acceptors for advanced organic electronic materials.
