[Rb4Sn9] — A Low Dimensional Arrangement of Zintl Ions in [Rb(18‐crown‐6)]2Rb2[Sn9](en)1.5

The compound Rb(18‐crown‐6)]₂Rb₂Sn₉](en)_1.5 ( 1 ) was synthesized from an alloy of formal composition K₂Rb₂Sn₉ by dissolving in ethylenediamine (en) followed by the addition of 18‐crown‐6 and toluene. 1 crystallizes in the monoclinic space group P2₁/n with a = 10.557(2), b = 25.837(5), c = 20.855(4)Å, β = 102.39°, and Z = 4. The structure consists of Sn₉]^4— cluster anions, which are connected via Rb atoms to infinite Rb₄Sn₉] layers. The layers of binary composition are separated by the crown ether molecules. The crown ether molecules are bound by one side via the Rb atoms to the Sn₉]^4— anions. The other side, which is turned away from the Rb atoms, shows only weak van der Waals interactions to the crown ether molecules of the next layer. Comparison with other compounds of similar composition shows, that the variation of the alkali metals and the complexing organic molecules leads to the low dimensional arrangement of the clusters.