Supertrityl Radical and Cation: The Effect of Large π-Surface for Intermolecular Interactions and Spin/Charge Delocalization

We report the synthesis and properties of a π-extended trityl radical and cation bearing three hexa-peri-hexabenzocoronenes (HBCs), that is, supertrityl radical and cations. X-ray analysis of cation revealed a propeller-shaped structure with two-dimensional honeycomb assembly through the π-π stacking on HBC units. The radical showed an equilibrium between monomer and dimer, and the computationally optimized dimer has not a σ-bond but a multicenter pancake bond. Despite the large π-surfaces, spin/charge remain mainly localized on the central carbon, resulting in high reactivity under ambient conditions. This behavior is rationalized by Clar’s aromatic sextet rule, offering design principles for π-surface–controlled radicals and cations.