Synthesis and crystal structure analysis of Sr₈Cu ₃In₄N₅ and Sr_0.53Ba _0.47CuN

Single crystals of new quaternary compounds Sr₈Cu ₃In₄N₅ and Sr_0.53Ba _0.47CuN were prepared, respectively, from a Sr-Cu-In-Na melt under 7MPa of N₂ and from a Sr-Ba-Cu-In-Na melt under 0.5MPa of N ₂ by slow cooling from 1023 to 823K. The crystal structures were determined by single-crystal X-ray diffraction. Sr₈Cu ₃In₄N₅ has an orthorhombic structure (space group, Immm, Z=2, a=3.8161(5)Å, b=12.437(2)Å, c=18.902(2)Å), and is isostructural with Ba₈Cu₃In₄N ₅. It contains nitridocuprates of isolated units ⁰[CuN₂] and one-dimensional linear chains _∝¹[CuN_2/2] and one-dimensional indium clusters _∝¹[In₂In_2/2]. Sr _0.53Ba_0.47CuN crystallizes in an orthorhombic cell, space group Pbcm, Z=4, a=5.4763(7)Å, b=9.2274(12)Å, c=9.0772(12)Å. The structure contains infinite zig-zag chains _∝ ¹[CuN_2/2] which kink at every second nitrogen atom.