Extraction of ternary alloys: Synthesis and crystal structure of [K([2.2.2]crypt)]Cs-7[Sn-9](2)(en)(3)

The compound [K([2.2.2]crypt)]Cs-7[Sn-9](2)(en)(3) (1) was synthesized from an alloy of formal composition KCs2Sn9 by dissolving in ethylenediamine (e n) followed by the addition of [2.2.2]crypt and toluene. 1 crystallizes in the orthorhombic space group Pcca with a = 45.38(2), b = 9.092(4), c = 18.4 59(8) A, and Z = 4. The structure consists Of Cs-7[Sn-9](2) layers which co ntain [Sn-9](4-) anions and Cs+ cations. The layers are separated by [K([2. 2.2]crypt)](+) units. In the intermetallic slab (Cs-7[Sn-9](2))(-) compares the arrangement of pairs of symmetry-related [Sng](4-) anions with the dim er ([Ge-9]-[Ge-9])(6-) in [K([2.2.2]crypt)](2)Cs-4([Ge-9]-[Ge-9]), in which the clusters are linked by a cluster-exo bond. The shortest distance betwe en atoms of such two clusters in 1 is 4.762 Angstrom, e. g. there are no ex o Sn-Sn bonds. The [Sn-9](4-) anion has almost perfect C-4v-symmetry.