(B3CB3)N2 Monolayer Consisting of CO2-Type Superatomic Molecules with Sandwich Hexacoordinate Carbons.

Abstract

Searching for a useful way to build stable hypercoordinate carbon species is a great way to enrich carbon-based chemical rules. Here, we extend the super valence bond model into superatom-atom superbonding to theoretically predict a two-dimensional (B3CB3)N2 monolayer, which is the first design of a stable nonplanar hexacoordinate carbon containing material, featuring a sandwich B3CB3 configuration. Chemical bonding analyses indicate that its stability originates from the unique super CO2 structures, where each tricoordinate B3 unit has six delocalized electrons acting as a super oxygen (S2P4), and the B3CB3 unit mimics the bonding pattern of the CO2 molecule via the superatom-atom super double bond. Thus, the (B3CB3)N2 monolayer can be visualized as an assembly of super CO2 units linked by N atoms. The calculated moderate direct band gap (∼1.71 eV) and high light absorption coefficient of the (B3CB3)N2 monolayer make it a promising candidate for further applications in electronics and optoelectronics. This work provides a possible pathway to design hypercoordinate carbon materials via superatom-atom cluster assembly, which is expected to be applied across diverse fields.