Synthesis and crystal structure of Sr₂ZnN₂ and Ba₂ZnN₂

Ternary nitrides, Sr₂ZnN₂ and Ba₂ZnN₂, were prepared from Sr or Ba along with Zn metal using Na metal and NaN₃ as a flux and nitrogen source, respectively. The single crystals were obtained by slow cooling from 750°C. Since these compounds hydrolyze in moist air, the crystals were isolated by washing away excess Na with liquid NH₃ in an inert environment. The structures were determined by single crystal X-ray diffraction: tetragonal, space group I 4/mmm with Z = 2, a = 3.8568(2), c = 12.935(1) Å, and R 1 = 0.049 for Sr₂ZnN₂, and a = 4.152(1), c = 13.055(3) Å, and R 1 = 0.039 for Ba₂ZnN₂. Sr₂ZnN₂ and Ba₂ZnN₂ are isostructural with Ca₂ZnN₂ (Na₂HgO₂ type) and contain linear [N=Zn=N]^4— nitridometallate anions.