Abstract: | Ca5[Si2Al2N8] was synthesized from elementary aluminum and silicon with phase‐pure tricalcium dinitride at 1280 K under dry argon in a sealed niobium ampoule. Ca3N2 was freshly prepared from distilled calcium metal in a dry nitrogen atmosphere. The compound crystallizes in form of transparent yellow distorted octahedra. In air and under moisture Ca5[Si2Al2N8] undergoes hydrolysis. The structure was determined from a single crystal to be orthorhombic (space group Pbcn – no. 60, a = 925.5, b = 614.0 and c = 1557.8 pm). The nitridoaluminate and ‐silicate substructures are separated into planes of edge and corner‐shared aluminate tetrahedra, which are linked by edge‐sharing double tetrahedral pillars of the silicate. The structure was confirmed by electrostatic and quantum mechanical analysis. |