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

Binary chalcogen halogen EX(4) species represent intriguing systems in terms of chemical bonding theories, such as hypervalency and stereoactivity of lone electron pairs. Instead of a simple molecular EX(4) structure, selenium tetrachloride forms an ionic pair, Cl(3)Se(+)Cl(-), that assembles into a tetrameric (SeCl(4))(4) structure, namely, tetra-μ(3)-chlorido-dodecachloridotetraselenium. This article describes the charge-density analysis of the tetrameric molecule of β-SeCl(4) based on the aspherical model obtained from Hirshfeld Atom Refinement of the tetrameric molecule and of an explicit cluster of 15 tetramers that simulates the crystal packing. Deformation density, electron localization function (ELF) and Quantum Theory of Atoms in Molecules (QTAIM) were used to evaluate the bonding situation, the electron-density distribution around the Se atom and the interaction energy of the tetramer.