Alkali metal germanides and stannides
Zintl cluster anions
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
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.
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