PB12 + and P2B12 +/0/-: The Novel B12 Cage Doped by Nonmetallic P Atoms

A new kind of nonmetallic atom-doped boron cluster is described herein theoretically. When a phosphorus atom is added to the B-12 motif and loses an electron, a novel B-12 cage is obtained, composed of two B-3 rings at both ends and one B-6 ring in the middle, forming a triangular bifrustum. Interestingly, this B-12 cage is formed by three B-7 units joined together from three directions at an angle of 120 degrees. When two P atoms are added to the B-12 motif, this novel B-12 cage is also obtained, and two P atoms are attached to the B-3 rings at both ends of the triangular bifrustum, forming a triangular bipyramid (Johnson solid). Amazingly, the global minimums of neutral, monocationic, and monoanionic P2B12+/0/- have the same cage structure with a D-3h symmetry; this is the smallest boron cage with the same structure. The P atom has five valence electrons, according to adaptive natural density partitioning bonding analyses of cage PB12+ and P2B12, in addition to one lone pair, the other three electrons of the P atom combine with an electron of each B atom on the B-3 ring to form three 2c-2e sigma bonds and form three electron sharing bonds with B atoms through covalent interactions, stabilizing the B-12 cage. The calculated photoelectron spectra can be compared with future experimental values and provide a theoretical basis for the identification and confirmation of PnB12- (n = 1-2).

Automated summary

A theoretical study on a new kind of nonmetallic atom-doped boron cluster is presented. The addition of a phosphorus atom to the B-12 motif results in the formation of a novel B-12 cage, composed of two B-3 rings at both ends and one B-6 ring in the middle, forming a triangular bifrustum. Further addition of two phosphorus atoms leads to the formation of a triangular bipyramid structure. The structures exhibit D-3h symmetry and provide a theoretical basis for future experimental investigations.