Synthesis of a derivative of triangulene; the first non-kekulé polynuclear aromatic

The first synthesis of a non-Kekulé polynuclear aromatic, a trioxy derivative of triangulene, has been achieved through a two-electron reduction of tetrabutylammonium 4,8-dioxo-4H,8H-dibenzo[cd,mn]pyren-12-olate 14. The single crystal X-ray diffraction structure of this precursor shows it to be essentially planar with a three-fold axis of symmetry. The trioxytriangulene produced when it is reduced also possesses a three-fold axis of symmetry and it has a triplet ground state. The powder ESR spectrum obtained is that for a uniaxial system fitted using the parameters |D/hc|= 0.0064 cm–1, |E/hc|= 0.0000 cm–1. It is stable at room temperature but very sensitive to sir oxidation.