Synthesis and crystal structures of the new ternary nitrides Sr3CrN3 and Ba3CrN3

Two new ternary nitrides, Sr3CrN3 and Ba3CrN3, were synthesised from the appropriate alkaline-earth-metal nitride and chromium metal or the chromium nitride, Cr2N, at high temperatures in sealed stainless-steel capsules. Structure determination from single-crystal X-ray data showed them to be isostructural in the hexagonal space group P63/m, Z= 2, with lattice constants a= 7.724(2), c= 5.249(1)Å for Sr3CrN3 and a= 8.201(2), c= 5.497(1)Å for Ba3CrN3. The structures contain trigonal-planar [CrN3]6– anions and either Sr2+ or Ba2+ cations.