Synthesis and crystal structures of [K(18-crown-6)][Rb(18-crown-6)]2Ge9 · 6NH3, [Rb(18-crown-6)]3Ge9 · 9NH3 and [Cs(18-crown-6)]3Ge9 · 6NH3

The new compounds [K(C12H24O6)][Rb(C12H24O6)]2Ge9 · 6NH3, [Rb(C12H24O6)]3Ge9 · 9NH3 and [Cs(C12H24O6)]3Ge9 · 6NH3 were prepared by the extraction of binary and ternary phases of the nominal composition K2Rb2Ge9, Rb4Ge9 and K2Cs2Ge9 with liquid ammonia in the presence of 18-crown-6. The resulting crystals were characterized by low temperature X-ray structure analysis. All of them contain the 21 electron cluster View the MathML sourceGe93-, which is coordinated by alkali metal cations in ion-paired arrangements. The cages were assigned their specific point group symmetry and were compared with hitherto known structures.