Layered Nitridomagnesogallates CaMg2GaN3 and CaMg2Ga2N4

• Published in: European journal of inorganic chemistry 2017-02, Vol.2017 (7), p.1067-1074
• Main Authors: Poesl, Christine, Neudert, Lukas, Schnick, Wolfgang
• Format: Article
• Language: English
• Subjects: Calcium; Gallates; Layered compounds; Magnesium; Nitrides; Solid‐state reactions; X‐ray diffraction
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201601381

The quaternary nitrides CaMg2GaN3 and CaMg2Ga2N4 were synthesized by means of solid‐state metathesis reactions. The crystal structures of both nitridomagnesogallates contain layers made up of either tetrahedral MN4 units (CaMg2Ga2N4) or both tetrahedral MN4 units and planar MN3 triangles (CaMg2GaN3) with mixed occupation of central atoms Mg and Ga. CaMg2GaN3 was obtained as a gray powder. Its crystal structure was determined on the basis of X‐ray powder diffraction data [P63/mmc (no. 194), a = 3.43093(8), c = 17.3989(5) Å, V = 177.368(9) Å3, Z = 2]. The compound is isotypic with CaMg2AlN3 and homeotypic with Ca2Mg5GeN6, ScAl3C3, and UAl3C3. The crystal structure of CaMg2Ga2N4 [P3m1(no. 164), a = 3.3859(3), c = 11.2378(11) Å, V = 111.57(2) Å3, Z = 1] was determined from single‐crystal X‐ray diffraction data and corroborated by Rietveld refinement. TEM investigations confirmed the metrics of both crystal structures and indicate the presence of both compounds as side products within one reaction batch. Structural similarities between CaMg2GaN3 and CaMg2Ga2N4 are discussed. CaMg2GaN3 and CaMg2Ga2N4 represent two novel nitridogallates with layered crystal structures. Syntheses were performed by employing solid‐state metathesis reactions, which is a new synthetic approach for nitridogallates. Owing to the strong structural relationship between both compounds, formation of composite crystals also seems likely.