Ba2Na(CN2)(CN)3, ein neues Cyanamid-cyanid mit interpenetrierenden Teilstrukturen / Ba2Na(CN2)(CN)3, a Novel Cyanamide Cyanide with Interpenetrating Substructures
Abstract Ba2Na(CN2)(CN)3 was obtained by the reaction of Ba2N with melamine and NaCN at 700 °C. The compound was structurally characterized by single-crystal X-ray investigations (Fd3̄m, a = 1518.8(3) pm, Z = 16). In the crystal structure the Ba2+ ions form a cubic close packed arrangement, the Na+ and the CN2-2 ions occupy the octahedral interstices. The CN-ions are located within the close packed Ba2+ layers. The unit cell of Ba2Na(CN2)(CN)3 contains two interpenetrating substructures of the zinc-blende structure type, building up a variant of NaTl. A reversible phase transition has been observed during cooling of the compound. Whereas the Ba2(CN2)(CN)3 sublattice remains nearly unaffected in this process, the Na+ ions of the low-temperature phase are statistically distributed on two crystallographic positions.