Ionic radii for Group 1 halide crystals and ion-pairs

Area of Science:

• Solid-state chemistry and physics
• Computational chemistry
• Inorganic chemistry

Background:

• Accurate internuclear separation is crucial for understanding chemical bonding and material properties.
• Group 1 halides exhibit diverse structures and bonding characteristics.
• Existing models for ionic radii may have limitations.

Purpose of the Study:

• To calculate and validate internuclear separations for Group 1 halides using empirical radii models.
• To compare soft-sphere and hovering-sphere radii with experimental data.
• To identify and analyze any anomalous ion-pair behavior.

Main Methods:

• Calculation of internuclear separations using empirical soft-sphere radii for crystalline rock-salt structures.
• Calculation of internuclear separations using empirical hovering-sphere radii for gaseous ion-pairs.
• Comparison of calculated separations with experimentally measured values.

Main Results:

• Good agreement was observed between calculated and experimental internuclear separations for most Group 1 halides.
• Two lithium and four fluoride ion-pairs exhibited deviations, indicating potential anomalies.
• Soft-sphere ionic radii were systematically compared with atomic radii of noble gases.

Conclusions:

• Empirical soft-sphere and hovering-sphere models provide reliable predictions for internuclear separations in many Group 1 halides.
• Anomalous behavior in specific lithium and fluoride ion-pairs warrants further investigation.
• The study contributes to a better understanding of ionic radii and their relationship to noble gas atomic radii.