Synthesis, structure and properties of SrAu3In3 and EuAu3In3—New indides with gold zig-zag chains

New indides SrAu3In3 and EuAu3In3 were synthesized by induction melting of the elements in sealed tantalum tubes. Both indides were characterized by X-ray diffraction on powders and single crystals. They crystallize with a new orthorhombic structure type: Pmmn, Z=2, a=455.26(9), b=775.9(2), c=904.9(2) pm, wR2=0.0425, 485 F2 values for SrAu3In3 and a=454.2(2), b=768.1(6), c=907.3(6) pm, wR2=0.0495, 551 F2 values for EuAu3In3 with 26 variables for each refinement. The gold and indium atoms build up three-dimensional [Au3In3] polyanionic networks, which leave distorted hexagonal channels for the strontium and europium atoms. Within the networks one observes Au2 atoms without Au–Au contacts and gold zig-zag chains (279 pm Au1–Au1 in EuAu3In3). The Au–In and In–In distances in EuAu3In3 range from 270 to 290 and from 305 to 355 pm. The europium atoms within the distorted hexagonal channels have coordination number 14 (8 Au+6 In). EuAu3In3 shows Curie–Weiss behavior above 50 K with an experimental magnetic moment of 8.1(1) μB/Eu atom. 151Eu Mössbauer spectra show a single signal at δ=−11.31(1) mm/s, compatible with divalent europium. No magnetic ordering was detected down to 3 K.