| Abstract
| - The stannide YbAuSn has been synthesized in quantitative yield by reacting the elementsin sealed tantalum tubes in a high-frequency furnace. The structure was determined fromsingle-crystal X-ray data: Imm2, a = 469.7(1) pm, b = 2191.2(4) pm, c = 812.7(1) pm,wR2 = 0.111, 2061 F2 values, and 58 variables. It crystallizes with a pronounced KHg2 typesubcell (a, 1/3b, c, Imma). In the superstructure the tripled b axis allows an ordered stackingof Au3Sn3 hexagons with weak gold−tin, gold−gold, and tin−tin interlayer bondinginteractions. The determined stacking sequence − + − − + −, − + − − + − in YbAuSnrealizes a so far missing sequence within a general ordering scheme of KHg2 typesuperstructures. The group−subgroup relation in going from the KHg2 subcell and chemicalbonding in YbAuSn are discussed. Each ytterbium site has an ordered near-neighborenvironment of six gold and six tin atoms in the form of two tilted hexagons. Magneticsusceptibility measurements show a nonmagnetic ground state of the ytterbium atoms.YbAuSn is a metallic conductor with a specific resistivity of 50 μΩ cm at room temperature.119Sn Mössbauer spectroscopic data show one signal at an isomer shift of 1.922(5) mm/ssubjected to quadrupole splitting of 0.929(9) mm/s.
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