Diversity in Nitridosilicate Chemistry: The Nitridoalumosilicate Ca₄(AlSiN₅) and the Nitridosilicate Silicide Ca₁₂Si₄[SiN₄]

Abstract

Dedicated to Prof. Dr. Caroline Röhr on the occasion of her 60 th birthday Single crystals of the calcium nitridoalumosilicate Ca 4 (AlSiN 5 ) and the nitridosilicate silicide Ca 12 Si 4 [SiN 4 ] were grown from sodium flux. Ca 4 (AlSiN 5 ) crystallizes in the noncentrosymmetric space group Pna2 1 and presents a framework of AlN 4 and SiN 4 tetrahedra sharing vertices. Ca 12 Si 4 [SiN 4 ] crystallizes in P � 1. Its crystal structure features mutually isolated nitridosilicate tetra-hedra [Si IV N 4 ] 8À next to Si 4À Zintl anions, with silicon both in its highest and lowest possible oxidation state. Crystals of the isotypic compound Sr 12 Ge 4 [GeN 4 ] were obtained, but the crystal structure could not be satisfactorily refined due to unsolved twinning issues.