Clusters of the Heavier Elements of Main Groups 14–16: A Novel Synthetic Route for Polyanions in Molten Crown Ether

Abstract

A novel procedure allows the synthesis of homoatomic polyanions directly from the elements E (E = Sn, As, Sb, Te) in molten A/18-crown-6 as reaction medium (A = K, Rb) at temperatures between 40 and 80° [1]. The reactions are carried out by adding E to mixtures of A and 18-crown-6 that proved to form stable melts under these conditions. Further work off using ethylenediamine or DMF as solvent yielded single crystals of the following compounds: [K(18-crown-6)]₄Sn₉ (1), [K(18-crown-6)]₃KSn₉·en (2), [K(18-crown-6)]₃As₇ (3), [K([2.2.2]crypt)]₂[K(18-crown-6)]Sb₇·0.5en (4), [Rb(18-crown-6)]₃Sb₇ (5), [K(18-crown-6)]₂Te₄ (6), and [K(18-crown-6)]₂Te₄·en (7). In all compounds short contacts between the Zintl ions and A-atoms are observed. The influence of cation-anion interactions on the structure of these anions is discussed.