Electrides with Dinitrogen Ligands.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Computational Materials Science

Background:

• Electrides are materials with excess electrons acting as anions within crystal cavities.
• Typically, electrides require a positive formal charge, necessitating detailed chemical bonding analysis for accurate identification.
• Potential electrides may be overlooked without rigorous bonding analysis.

Purpose of the Study:

• To survey and identify potential electrides that might be missed by conventional methods.
• To explore novel electride compounds using advanced computational techniques.
• To investigate the role of dinitrogen ligands in electride formation and properties.

Main Methods:

• Application of various structure sampling techniques.
• Utilizing first-principles calculations for material prediction.
• High-throughput screening for identifying known and novel electride candidates.

Main Results:

• Prediction of two novel electride compounds: Ba₂N₂:e⁻ and Li₂Ca₃N₆:2e⁻, both containing dinitrogen ligands.
• Identification of Li₂Ca₃N₆:2e⁻ (with [N₂]²⁻) as an electride for the first time, despite prior synthesis.
• Discovery of Ba₂N₂:e⁻ (with [N₂]³⁻) as a completely new electride compound via first-principles prediction.
• Observation of different valence states in dinitrogen ligands, suggesting tunable electronic properties.

Conclusions:

• Established a new class of inorganic electrides featuring dinitrogen ligands.
• Demonstrated a novel approach to tune the concentration and anisotropic properties of anionic interstitial electrons.
• Validated the predictive power of modern crystal structure sampling techniques for rational material design.