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 900 K in sealed niobium ampoules. The compound forms plate-like crystals with silver metallic luster, which are very unstable in air and moisture. The crystal structure of K2NaInSb2 has been determined using single-crystal X-ray diffraction methods (space group Cmca (No. 64); a = 14.032(2), b = 16.399(3), c = 7.009(1) angstrom; Z = 8; Pearson symbol oC48). The structure contains pairs of edge-sharing InSb4 tetrahedra which 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 interconnected by K+ cations. The whole structure can be considered as an ordered derivative of the KMnP structure (PbFCl type).