Bonding properties and crystal packing in β-(SeCl₄)₄ derived from Hirshfeld Atom Refinement

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Crystallography

Background:

• Binary chalcogen halides (EX4) are key for understanding hypervalency and lone pair stereoactivity.
• Selenium tetrachloride (SeCl4) deviates from simple EX4 structures, existing as an ionic pair (Cl3Se+Cl-) that forms a tetrameric structure.

Purpose of the Study:

• To perform a charge-density analysis of the tetrameric molecule of beta-selenium tetrachloride (β-SeCl4).
• To investigate the bonding situation, electron density distribution around selenium atoms, and interaction energy within the tetramer.

Main Methods:

• Charge-density analysis using Hirshfeld Atom Refinement on a tetrameric molecule and a 15-tetramer cluster simulating crystal packing.
• Application of deformation density, electron localization function (ELF), and Quantum Theory of Atoms in Molecules (QTAIM) analyses.

Main Results:

• Detailed charge-density distribution and bonding characteristics of the tetrameric β-SeCl4 structure were elucidated.
• Analysis provided insights into the electronic environment around the selenium atoms and the nature of inter- and intra-tetramer interactions.

Conclusions:

• The study confirms the complex, non-molecular structure of SeCl4 and provides a deep understanding of its electronic properties.
• Findings contribute to the broader understanding of bonding theories, particularly hypervalency, in chalcogen halide systems.