K₂BaSi₄: Zintl Concept in Position Space

Abstract

The Zintl phase K2BaSi4 has been synthesized from the mixture of precursors KSi and BaSi2. The crystal structure of K2BaSi4 was elucidated from X‐ray powder diffraction data: Pearson symbol oP28, space group Pbcm, a=9.4950(1), b=9.2392(1), c=9.9025(1) Å. The main building block of the crystal structure are tetrahedral anions Si44–. Analysis of chemical bonding for K2BaSi4 and its chemical analogs – molecular H4Si4 and solid state K4Si4 employing the electron localizability approach reveals the basic agreement with the Zintl model in terms of number of basins for Si−Si bonds and lone pairs at Si atoms, as well as the charge transfer direction. The populations of the bond and ‘lone‐pair’ basins agree with the Zintl count for molecular species and deviate strongly for the solids, in particular, while the ‘lone‐pair’ basins are over‐populated, the bond basins are essentially under‐populated. The topology of the calculated electron density and electron‐localizability indicator is very sensitive toward the interatomic distances and angles in the Si44− anion.

Crystal Structure and Magnetic Properties of High‐Pressure Phases RESi3 (RE=Tb, Dy, Er, Tm)

“…The qualitative appropriateness of this simple, yet powerful empirical counting scheme for Zintl phases has also been confirmed by advanced analysis of the chemical bonding in position space. [4,5] In binary systems of silicon and the alkaline-earth metals, the silicon-richest ambient-pressure phases are often electron-precise MSi 2 compounds with three-bonded silicon atoms (for M = Ca or Sr).…”

[Tl7]7– Clusters in Mixed Alkali Metal Thallides Cs7.29K5.71Tl13 and Cs3.45K3.55Tl7

“…Salt-like Zintl phases including isolated clusters are of great interest in material science, as they provide p-block metal building blocks, which can be transferred and altered using solution chemistry methods. − For homoatomic clusters, this is proven for groups 14–16. In contrast, no group 13 cluster has yet been obtained from dissolving trielide Zintl phases.…”