Abstract

The antimonides Ce₂Ir₃Sb₄, La₂Ir₃Sb₄, and Ce₂Rh₃Sb₄ were synthesized by solid state reaction from the elements. The crystal structures of these compounds were determined from single crystal X-ray diffraction data. Ce₂Ir₃Sb₄ crystallises in a new structure type in the space group Pnma (no. 62) with a = 16.1510(8) Å, b = 4.5600(3) Å, c = 10.9463(5) Å. La₂Ir₃Sb₄ and Ce₂Rh₃Sb₄ crystallise in the Ce₂Ir₃Sb₄ structure type as well with a = 16.2659(10) Å, b = 4.5896(3) Å, c = 10.9996(7) Å) and a = 16.2293(8) Å, b = 4.5604(2) Å, c = 10.9804(5) Å, respectively. The four- and five-bonded transition metal atoms and three- and four-bounded Sb atoms form a 3D-network with the rare-earth metal embedded in its cavities, resembling the topology of Ca in the CaBe₂Ge₂ or Th in ThCr₂Si₂ type. Magnetic susceptibility and X-ray absorption near edge spectroscopy data indicate a stable trivalent state for Ce in the Ce₂Ir₃Sb₄ compound.