Aromatic Rules of C 22 H 12 2+/2•/2- : Flexibility in Electronic Structures of 2D Superatomic Molecules.

Triangulene (C 22 H 12 2• ), a nonclassic non-Kekulé polycyclic aromatic hydrocarbon, is identified to be aromatic by structural and magnetic criteria. However, its aromatic origin remains confusing. Herein, the aromatic rules of C 22 H 12 2• and its two charged counterparts C 22 H 12 2+/2- were investigated on the basis of a recently developed two-dimensional (2D) superatomic-molecule theory. [C 22 H 12 ] 2+/2•/2- exhibit obvious local aromatic characters and can be regarded as [ ◊ N 3 ◊ O 3 ] + , [ ◊ N 3 ◊ O 3 ] - , and ◊ N 3 ◊ F 3 superatomic molecules, respectively, where ◊ N, ◊ O, and ◊ F denote 2D superatoms bearing 3π, 4π, and 5π electrons. [C 22 H 12 ] 2+/2- realize electronic shell closure via superatomic lone pairs and covalent bonds, mimicking simple molecules, whereas the α-π and β-π electrons in C 22 H 12 2• follow the superatomic bonding patterns of C 22 H 12 2- and C 22 H 12 2+ , respectively. Furthermore, based on the local character in 2D superatomic molecules, a doped nanoporous graphene, namely, C 9 N 12 B monolayer, was predicted. The material possesses excellent dynamical and thermodynamical stability, as well as a wide band gap of 2.77 eV, positioning it as a promising 2D material for future electronic applications.