Crystal Growth and Structure Refinement of K 4 Ge 9

Deep‐red moisture and air sensitive single crystals of K 4 Ge 9 were obtained by reacting GeO 2 and elemental Ge with metallic W and K at high temperature in a niobium ampoule. The crystal structure of the compound was determined by single crystal X‐ray diffraction experiments. K 4 Ge 9 crystallizes in a polar space group R 3 c (No. 161), Z = 4 with a = 21.208(1) and c = 25.096(2) Å. The compound contains discrete Ge 9 4− Wade's nido ‐clusters which are packed according to a hierarchical atom‐to‐cluster replacement of the Cr 3 Si prototype and are separated by K + cations. Two independent [Ge 9 ] 4− clusters A (at Cr positions) and B (at Si positions) are found with a ratio A:B = 3:1. The B ‐type cluster satisfactorily represents orientational disorder around the three‐fold axis.