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Abstract

Abstract Polycrystalline samples YbIn1?xAu1+x were prepared by reaction of the elements in sealed tantalum tubes at 1170 K with a subsequent annealing at 770 K. The crystal structures of YbInAu (space group P6;?2m, a = 7.6992(8), c = 4.0333(5) Å, wR2 = 0.035, 282 reflections and 14 variables) and YbIn0.73Au1.27 (P6;?2m, a = 7.706(3), c = 4.011(1) pm, wR2 = 0.035, 275 reflections, 14 parameters) were refined from single crystal X?ray diffraction data. The phase YbIn1?xAu1+x has a homogeneity range for 0.0≤x≤0.3 (770 K). The crystal structure of YbInAu contains two gold atoms located in tricapped trigonal prisms [Au1Yb6In3] and [Au2In6Yb3]. The indium position shows mixed occupancy by indium and gold. The main atomic interaction is the ionic one between the ytterbium (charge +1.1 is obtained from the analysis of the electron density within the quantum theory of atoms in molecules) and gold (?1.2 and ?1.3) supported by the dative bonding Au?Yb. The effective charge of indium is +0.2. Magnetic susceptibility data indicate intermediate valence for Yb increasing with increasing x. The 197Au Mössbauer spectra show a superposition of the signals for Au1 (δ = 3.31 mm s?1), Au2 (δ = 5.37 mm s?1), and Au(In) indicating auridic character of gold.