Generalized Octet Rule with Fractional Occupancies for Boron

Area of Science:

• Inorganic Chemistry
• Materials Science
• Theoretical Chemistry

Background:

• The conventional octet rule is insufficient for explaining electron delocalization in boron allotropes and boron-rich compounds.
• Boron's inherent electron deficiency challenges traditional bonding models.
• Lewis structures fail to capture the complexity of bonding in these systems.

Purpose of the Study:

• To develop a more accurate model for chemical bonding in electron-deficient systems, specifically boron.
• To introduce the concept of fractional electron occupancies to describe electron delocalization.
• To propose a generalized octet rule applicable to boron allotropes and related compounds.

Main Methods:

• Introduction of fractional electron occupancies as a descriptor for electron distribution.
• Formulation of a generalized octet rule based on these fractional occupancies.
• Validation using first-principles calculations and comparison with experimental data for α-B₁₂.

Main Results:

• Fractional electron occupancies provide a more accurate depiction of electron delocalization in boron systems.
• The generalized octet rule successfully explains complex bonding configurations in boron allotropes.
• Predictions for α-B₁₂ align with computational and experimental findings.

Conclusions:

• The generalized octet rule offers a superior framework for understanding chemical bonding in boron-rich materials.
• This model extends beyond boron to systems exhibiting multiple resonance structures.
• Fractional electron occupancies represent a key advancement in describing electron delocalization.