Three-Supercenter Two-Electron Bonds in CH: Two-Dimensional Analogue of Halogen-Bridge Bonding.

Three-center two-electron bridging bonding plays a vital role in rationalizing structures and stabilities of certain molecules. Herein, the π electron rule of pyrene (CH) was unraveled based on a newly proposed two-dimensional (2D) superatomic-molecule theory, where the superatomic sextet rule was regarded as a π electron counting target. CH can be taken as a NF superatomic molecule, where N and F denote 2D superatoms bearing 3π and 5π electrons, respectively. Interestingly, it represents the first 2D superatomic halogen-bridge molecule, which realizes π electronic shell-closure via two three-supercenter two-electron bridging bonds. Additionally, a N-doped nanoporous graphene with a wide band gap (1.22 eV) was designed based on CH, which can be considered as a periodic aggregate of 2D superatomic wires composed of 2π-C and bridging F superatoms. This work enriches the 2D superatomic-molecule chemistry and provides a practicable bottom-up assemble approach to obtain 2D functional materials with tunable band gaps.