Binary alkali metal compounds with the zintl anions [Ge₉]⁴⁻ and [Sn₉]⁴⁻

Abstract

The binary germanides M12Ge17 and M4Ge9 (M  Na, K, Rb, Cs) and the stannides M12Sn17 and M4Sn9 (M  K, Rb, Cs) were identified by a combination of direct synthesis, thermogravimetric analysis, vibrational spectroscopy, X‐ray powder data and single crystal structure analysis. The M12E17 phases contain the cluster anions [E9]4− and [E4]4− in the ratio 1:2, forming a hierarchical structure with the cluster anions at the atomic positions of the hexagonal Laves phase MgZn2. Like the M4E4 phases, the M4Ge9 compounds are hierarchical derivatives of the cubic Cr3Si structure but with [Ge9]4− anions. The thermogravimetric analyses give strong evidence for the existence of at least one more phase with [E9]4− and [E4]4− clusters and of the clathrate phases M6E136 in addition to the well‐known M8E44□2 chlathrates.

On the Structure of Nonastannide Clusters in Liquid and Solid State

“…[25] This peak is assigned to the symmetrical breathing mode of vibration. Similar spectra were observed for the Na:Sn system.…”

Polyanionic Clusters and Networks of the Early p-Element Metals in the Solid State: Beyond the Zintl Boundary

“…[60] It should be noted that additional evidence for Ge 9 4À and Sn 9 4À species, including these species as neat sodium salts, has been obtained by the von Schnering group from synthetic, X-ray powder diffraction, and vibrational spectroscopic studies but without clear X-ray resolution of the two structure types due to poor crystal quality (twinning, high pseudosymmetry). [61] (The results from Sevov et al generally pertain to larger cations. )…”

The [Sn5]2-Cluster Compound [K-(2,2,2-crypt)]2Sn5- Synthesis, Crystal Structure, Raman Spectrum, and Hierarchical Relationship to CaIn2

“…4± cluster anions with E = Si, Ge, Sn [2,3]. Again, the characteristic breathing mode mª 1 (A' 1 ) has the largest intensity and the wave numbers 180 cm ±1 (K) and 181 cm ±1 (Na), respectively.…”