Cyclic carbon cluster dianions and their aromaticity.

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Materials Science

Background:

• Carbon clusters are fundamental building blocks in chemistry.
• Understanding the properties of novel carbon allotropes is crucial.
• Dianions of carbon clusters offer unique electronic and structural characteristics.

Purpose of the Study:

• To investigate the geometric properties, electronic stability, and aromaticity of cyclic carbon cluster dianions (CC(2))(2-)(n) for n = 3-6.
• To determine the stability of these dianions in the gas phase.
• To explore the relationship between ring size and aromatic character.

Main Methods:

• Ab initio computational methods were employed.
• Geometric optimizations were performed to determine stable structures.
• Electronic stability and aromaticity were assessed using theoretical analyses.

Main Results:

• All investigated cyclic carbon cluster dianions (CC(2))(2-)(n) (n=3-6) are stable in the gas phase.
• Unique wheel-like structures were observed, featuring a central carbon ring with C(2) units.
• The smallest cluster, (CC(2))(2-)(3), exhibits clear aromaticity, which decreases with increasing ring size.
• Resonance structure arguments effectively explain the observed geometries and aromaticity trends.

Conclusions:

• Cyclic carbon cluster dianions (CC(2))(2-)(n) are stable species with intriguing wheel-like geometries.
• Aromaticity is a significant feature, particularly in smaller clusters, and is size-dependent.
• The findings provide insights into the fundamental chemistry of carbon clusters and their potential for novel materials.