Boron avoids cycloalkane-like structures in the Li n B n H 2n series

• Published in: New journal of chemistry 2016, Vol.40 (3), p.2007-2013
• Main Authors: Vásquez-Espinal, Alejandro, Torres-Vega, Juan J., Alvarez-Thon, Luis, Fuentealba, Patricio, Islas, Rafael, Tiznado, William
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C5NJ02051D

The stability of the Li n B n H 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 n H 2n ), where cyclopentane (C 5 H 10 ) and cyclohexane (C 6 H 12 ) 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 Li 3 B 3 H 3 + system, which has been designed as the smallest aromatic carbocation (C 3 H 3 + ) analogue. The global minimum structure of Li 3 B 3 H 3 + contains a triangular B 3 H 3 2− 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 4 n + 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.