Geometry, stability, and isomerization of B_nN_2 (n = 1-6) isomers

摘要

We perform a systematic study on the geometry, stability, nature of bonding, and potential energy surface of low-lying isomers of planar and cyclic B_nN_2 (n = 1-6) at the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) level. B_nN_2 (n = 2-4) clusters are structurally similar to pure boron clusters. The evolution of the binding energy per atom, incremental binding energy, and second-order difference of total energy with the size of B_nN_2 reveals that the lowest energy isomer of B_3N_2 has high stability. B_5N_2 and B_6N_2 possess π-aromaticity according to Hückel (4n + 2) rule. The aromaticity of some isomers of B_4N_2 and B_6N_2 is examined based on their valence molecular orbitals. At the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) level, several B _2N_2, B_3N_2, B_4N _2, and B_5N_2 isomers are predicted to be stable both thermodynamically and kinetically, and detectable in future experiments.