Ternary CaBe₂B₇^- Cluster: A Turning Nanoclock

Area of Science:

• Materials Science
• Computational Chemistry
• Inorganic Chemistry

Background:

• Boron-based alloy clusters possess unique properties like exotic bonding and dynamic behavior.
• Understanding these clusters is key to developing new materials and chemical functionalities.

Purpose of the Study:

• To rationally design and characterize a novel ternary boron-based alloy cluster.
• To investigate the structural, electronic, and bonding properties of the designed cluster.
• To explore the potential of heptagonal boron rings as inorganic ligands.

Main Methods:

• Global structural searches were employed to identify potential cluster structures.
• Electronic structure calculations were performed to analyze properties.
• High-level single-point coupled cluster with double and triple excitations (CCSD(T)) calculations determined rotation barriers.
• Chemical bonding analysis elucidated the nature of interactions within the cluster.

Main Results:

• A ternary CaBe2B7- cluster with a quasi-triple-layered structure was successfully designed.
• The cluster exhibits significant dynamic structural fluxionality, akin to a subnanoscale turning clock.
• A very low intramolecular rotation barrier (0.08 kcal mol-1) was calculated.
• The system displays double 6π/6σ aromaticity, contributing to its stability and fluxionality.

Conclusions:

• The designed CaBe2B7- cluster represents a novel structure with remarkable dynamic properties.
• Double aromaticity is identified as a key factor for the cluster's stability and fluxional behavior.
• The heptagonal [B7]5- ring motif shows promise as a versatile inorganic ligand in future chemical explorations.