Complex Three-Dimensional [Au3In5] Polyanions in Ln2Au3In5 (Ln=Ce, Pr, Nd, Sm)

Abstract

The four isotypic title compounds were prepared from the elements by reactions in an arc-melting furnace and subsequent annealing in sealed silica tubes at 970 K. The structure of the cerium compound was solved from single crystal X-ray diffractometer data: Pmn21, oP80, a=465.27(8) pm, b=5348.3(9) pm, c=740.5(1) pm, R1=0.0735, 5552 F2 values, 243 variables, and BASF=0.48(2). The structure of Ce2Au3In5 is composed of a complex three-dimensional [Au3In5] polyanion with a large variety of Au–In and In–In bonds. The cerium atoms are embedded in distorted pentagonal and hexagonal channels within this polyanion. The crystal chemical relationship of the Ce2Au3In5 structure with the structures of the related stannides Y2Rh3Sn5 (oC40, Cmc21) and Yb2Pt3Sn5 (oP40, Pnma) is discussed. The differences in these three structure types result from a different ordering of the transition metal and tin(indium) atoms within the polyanionic network. Temperature-dependent magnetic susceptibility measurements of Ce2Au3In5 show modified Curie–Weiss behavior with χ0=5.2×10−9 m3/mol, Θ=−16(1) K, and μexp=2.51(2) μB/Ce, indicating trivalent cerium. No magnetic ordering could be observed down to 2 K.