DIPOTASSIUM SODIUM DIANTIMONIDOINDATE, K2NA[INSB2], A COMPOUND WITH THE POLYANION INFINITY-2[IN2SB2SB4 2]6-/

The novel compound K2Na[InSb2] was synthesized from the elements at 90 0 K in sealed niobium ampoules. The compound forms plate-like crystals with silver metallic luster, which are very unstable in air and moist ure. The crystal structure of K2NaInSb2 has been determined using sing le-crystal X-ray diffraction methods (space group Cmca (No. 64); a = 1 4.032(2), b = 16.399(3), c = 7.009(1) angstrom; Z = 8; Pearson symbol oC48). The structure contains pairs of edge-sharing InSb4 tetrahedra w hich are linked to four other pairs via common vertices and form a two -dimensional infinity 2[In2Sb2Sb4/2]6- anionic partial structure. The resulting pairs of tetrahedral holes are filled by Na+ cations. These [In2Sb2Sb4/2]6- layers are stacked along the b-axis and are interconne cted by K+ cations. The whole structure can be considered as an ordere d derivative of the KMnP structure (PbFCl type).