The sigma delocalization in planar boron clusters

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Aromaticity in boron clusters is crucial for their stability and properties.
• Understanding electron delocalization is key to explaining bonding and stability in these systems.
• Previous studies highlight the importance of sigma delocalization in small boron clusters.

Purpose of the Study:

• To investigate the distinct delocalization behaviors of sigma and pi electrons in boron clusters.
• To determine the factors influencing sigma electron delocalization and its relationship with ring size.
• To assess the applicability of the Hückel rule to the pi subsystem of boron clusters.

Main Methods:

• Electron Localization Function (ELF) calculations were employed.
• Analysis of electron delocalization patterns for both sigma and pi electrons.
• Correlation of delocalization with cluster size and electronic structure.

Main Results:

• Sigma and pi electrons exhibit different delocalization patterns.
• Sigma electron delocalization is primarily driven by radial p(sigma) overlapping, decreasing with increasing ring size.
• The Hückel rule accurately predicts aromaticity for the pi subsystem across all cluster sizes.

Conclusions:

• Distinct mechanisms govern sigma and pi electron delocalization in boron clusters.
• Small boron rings are expected to exhibit significant sigma electron delocalization.
• The Hückel rule remains a valid predictor of aromaticity for the pi system in boron clusters, irrespective of size.