Atomically Precise Synthesis and Characterization of Heptauthrene with Triplet Ground State

This is the authors' abstract. We don't add key points for this paper.

phenalenyls in mirror symmetry and expected to have a triplet ground state. However, the synthesis of unsubstituted heptauthrene remains very challenging due to the high reactivity of triplet diradicals. Here, we report a combined in-solution and on-surface synthesis of unsubstituted heptauthrene, whose chemical structure is characterized through bond-resolved atomic force microscopy. Combined with mean-field Hubbard model calculations, its triplet ground state is unambiguously confirmed by the underscreened Kondo resonance in response to the magnetic field, as well as the engineered spin-state switching upon extra hydrogen atom addition and dissociation on the radical site. Our results provide access to phenalenyl-based nanographenes with high-spin ground state, potentially useful in constructing high-spin networks.