Electronic Structure and Electron Delocalization in Bare and Dressed Boron Pentamer Clusters

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Boron clusters are of interest due to their unique electronic properties and potential applications.
• Understanding the electronic structure and bonding in small boron clusters is crucial for predicting their behavior.

Purpose of the Study:

• To investigate the electronic structures of cationic, neutral, and anionic boron pentamer clusters.
• To analyze electron delocalization and chemical bonding in different spin states.
• To explore the impact of ligands on the geometry and electronic properties of boron pentamers.

Main Methods:

• High-level multiconfigurational calculations were employed.
• Analysis of electron delocalization using normalized Giambiagi ring-current index and delocalization indices.
• Explicit all-electron calculations.

Main Results:

• The singlet spin-state of the bare boron pentamer resembles a perfect pentagon with no intra-annular bonding.
• Triplet and quintet spin-state isomers exhibit C2 symmetry and significant intra-annular bonding.
• Neutral and anionic boron pentamers show peripheral and intra-annular bonding, leading to structural stability.
• The lowest energy triplet spin-state isomer of the anionic boron pentamer cluster is predicted to be optically active.
• Ligand bonding induces a transition from planar to 3D structures, explained by the jellium model.

Conclusions:

• The electronic structure and spin state significantly influence the bonding and geometry of boron pentamer clusters.
• Anionic boron pentamers with specific symmetries are predicted to exhibit optical activity.
• Ligands play a key role in modulating the electronic and structural properties of boron clusters.