Chemical Bonding and Dynamic Structural Fluxionality of a Boron-Based B<sub>8</sub>Al<sub>3</sub><sup>+</sup> Cluster

We studied the boron-based composite cluster B<sub>8</sub>Al<sub>3</sub><sup>+</sup> doped with Al atoms. The global minimum structure of the B<sub>8</sub>Al<sub>3</sub><sup>+</sup> cluster is a three-layer structure, consisting...

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Bibliographic Details
Main Authors: Shu-Juan Gao, Tan-Lai Yu
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/24/5961
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Summary:We studied the boron-based composite cluster B<sub>8</sub>Al<sub>3</sub><sup>+</sup> doped with Al atoms. The global minimum structure of the B<sub>8</sub>Al<sub>3</sub><sup>+</sup> cluster is a three-layer structure, consisting of three parts: an Al<sub>2</sub> unit, a B<sub>8</sub> ring and an isolated Al atom. Charge calculations analysis shows that the cluster can be expressed as [Al]<sup>+</sup>[B<sub>8</sub>]<sup>2−</sup>[Al<sub>2</sub>]<sup>2+</sup>, has 6π/6σ double aromaticity and follows the (4<i>n</i>+2) Hückel rule. Born–Oppenheimer molecular dynamics (BOMD) simulation shows that the B<sub>8</sub>Al<sub>3</sub><sup>+</sup> cluster has dynamic fluxionality properties. Remarkably, at the single-point coupled cluster singles, doubles and triples (CCSD(T)) level, the energy barrier for intramolecular rotation is merely 0.19 kcal mol<sup>−1</sup>. [B<sub>8</sub>]<sup>2−</sup> molecular wheels have magical 6π/6σ double aromaticity properties, providing a continuous cloud of delocalized electrons, which is a key factor in the dynamic fluxionality of the cluster. The B<sub>8</sub>Al<sub>3</sub><sup>+</sup> cluster provides a new example of dynamic structural fluxionality in molecular systems.
ISSN:1420-3049