Synthesis and Structure of Two New Strontium Germanium Nitrides: Sr₃Ge₂N₂ and Sr₂GeN₂

We report the structures of two new strontium germanium nitrides synthesized as crystals from the elements in sealed Nb tubes at 750 °C using liquid Na as a growth medium. Sr3Ge2N2 is isostructural with the previously reported Ba analogue. It crystallizes in P21/m (No. 11), with a = 9.032(2) Å, b = 3.883(1) Å, c = 9.648(2) Å and β = 112.42(3)°, and has two formula units per unit cell. It contains GeN24- units and additionally |Ge2- zigzag chains. Sr2GeN2 crystallizes in P42/mbc (No. 135) with a = b = 11.773(2) Å and c = 5.409(1) Å and has Z = 8. It also contains GeN24- units which have 18 valence electrons and, consequently are bent, like the isoelectronic molecule SO2.