Boron avoids cycloalkane-like structures in the LinBnH2n series.

The stability of the Li_nB_nH_2n (n = 3–6) series was analyzed using quantum chemical calculations, and it was found that cyclic isomers are not energetically favored. This is different to what happens in their organic counterparts (C_nH_2n), where cyclopentane (C₅H₁₀) and cyclohexane (C₆H₁₂) are the low-lying isomers. Apparently, aromaticity is a key-stabilizing factor that needs to be considered for designing stable lithium-boron hydride analogues of cyclic organic compounds. This is verified in the Li₃B₃H₃⁺ system, which has been designed as the smallest aromatic carbocation (C₃H₃⁺) analogue. The global minimum structure of Li₃B₃H₃⁺ contains a triangular B₃H₃²⁻ moiety, which has structural and chemical bonding features similar to its organic counterpart. Besides, this new cluster is classified as aromatic according to both the 4n + 2 Hückel rule and the analysis of the induced magnetic field. This theoretical evidence leads us to propose this cluster as a viable target for experimental detection in the gas phase. [ABSTRACT FROM AUTHOR]