• boron–carbon cluster;
  • stability;
  • potential energy surface;
  • density functional theory

The structures, stabilities, nature of bonding, and potential energy surfaces of low-energy isomers of planar CnB5 (n = 1−7) have been systematically explored at the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) level. Incremental binding energy (IBE) and second order energy difference (Δ2E) analyses demonstrate that CnB5 clusters with even n have relatively higher stability. The nature of bonding in these clusters is discussed based on valence molecular orbital (VMO), and Mayer bond order (MBO). Hückel (4n + 2) rule and nucleus-independent chemical shift (NICS) values suggest that the ground states of C3B5, C4B5, and C7B5 have π aromaticity. VMO, electron localization function (ELF), adaptive natural density partitioning (AdNDP), and NICS analyses reveal the double aromaticity of C3B5 cation. CB5 and C3B5 are stable both thermodynamically and kinetically based on isomerization analysis. In addition, the simulated IR spectra are expected to be helpful for future experimental studies of these clusters.