(B<sub>3</sub>CB<sub>3</sub>)N<sub>2</sub> Monolayer\nConsisting of CO<sub>2</sub>‑Type Superatomic Molecules with\nSandwich Hexacoordinate Carbons

Searching\nfor a useful way to build stable hypercoordinate carbon\nspecies is a great way to enrich carbon-based chemical rules. Here,\nwe extend the super valence bond model into superatom–atom\nsuperbonding to theoretically predict a two-dimensional (B<sub>3</sub>CB<sub>3</sub>)N<sub>2</sub> monolayer, which is the first design\nof a stable nonplanar hexacoordinate carbon containing material, featuring\na sandwich B<sub>3</sub>CB<sub>3</sub> configuration. Chemical bonding\nanalyses indicate that its stability originates from the unique super\nCO<sub>2</sub> structures, where each tricoordinate B<sub>3</sub> unit\nhas six delocalized electrons acting as a super oxygen (S<sup>2</sup>P<sup>4</sup>), and the B<sub>3</sub>CB<sub>3</sub> unit mimics the\nbonding pattern of the CO<sub>2</sub> molecule via the superatom–atom\nsuper double bond. Thus, the (B<sub>3</sub>CB<sub>3</sub>)N<sub>2</sub> monolayer can be visualized as an assembly of super CO<sub>2</sub> units linked by N atoms. The calculated moderate direct band gap\n(∼1.71 eV) and high light absorption coefficient of the (B<sub>3</sub>CB<sub>3</sub>)N<sub>2</sub> monolayer make it a promising\ncandidate for further applications in electronics and optoelectronics.\nThis work provides a possible pathway to design hypercoordinate carbon\nmaterials via superatom–atom cluster assembly, which is expected\nto be applied across diverse fields.