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 degrees C using liquid Na as a growth medium. Sr(3)Ge(2)N(2) is isostructural with the previously reported Ba analogue. It crystallizes in P2(1)/m (No. 11), with a = 9.032(2) Å, b = 3.883(1) Å, c = 9.648(2) Å and beta = 112.42(3) degrees, and has two formula units per unit cell. It contains GeN(2)(4)(-) units and additionally |Ge(2)(-) zigzag chains. Sr(2)GeN(2) crystallizes in P4(2)/mbc (No. 135) with a= b = 11.773(2) Å and c= 5.409(1) Å and has Z = 8. It also contains GeN(2)(4)(-) units which have 18 valence electrons and, consequently are bent, like the isoelectronic molecule SO(2).