Li2 B12 and Li3 B12 : Prediction of the Smallest Tubular and Cage-like Boron Structures

Abstract

An intriguing structural transition from the quasi-planar form of B₁₂ cluster upon the interaction with lithium atoms is reported. High-level computations show that the lowest energy structures of LiB₁₂ , Li₂ B₁₂ , and Li₃ B₁₂ have quasi-planar (C_s ), tubular (D_6d ), and cage-like (C_s ) geometries, respectively. The energetic cost of distorting the B₁₂ quasi-planar fragment is overcompensated by an enhanced electrostatic interaction between the Li cations and the tubular or cage-like B₁₂ fragments, which is the main reason of such drastic structural changes, resulting in the smallest tubular (Li₂ B₁₂ ) and cage-like (Li₃ B₁₂ ) boron structures reported to date.

Keywords: boron clusters; electrostatic interactions; high-level computations; structural transitions; tubular structures.