Lu${}_{20}$Ir${}_5$In${}_3$ and Lu${}_{20}$Pt${}_5$In${}_3$ - superstructures of the Al${}_5$Co${}_2$ type by coloring and distortion

The lutetium-rich intermetallic compounds Lu${}_{20}$Ir${}_5$In${}_3$ and Lu${}_{20}$Pt${}_5$In${}_3$ were synthesized from the elements in sealed tantalum ampules in an induction furnace. The phase purity of the samples was checked by powder X-ray diffraction. The structures of Lu${}_{20}$Ir${}_5$In${}_3$ and Lu${}_{20}$Pt${}_5$In${}_3$ were refined from single crystal X-ray diffractometer data: P$\overline{6}$2m, a=1618.53(4), c=919.36(4) pm, wR2=0.0588, 2665 F${}^2$ values, 88 variables for Lu${}_{20}$Ir${}_5$In${}_3$ and a=1630.58(4), c=920.43(4) pm, wR2=0.0836, 3024 F${}^2$ values, 89 variables for Lu${}_{19.92}$Pt${}_5$In${}_3$. The platinum compound showed small amounts of defects on one lutetium site. Lu${}_{20}$Ir${}_5$In${}_3$ and Lu${}_{20}$Pt${}_5$In${}_3$ are non-centrosymmetric superstructures (through coloring and distortions) that derive from the aristotype Al${}_5$Co${}_2$ via two steps of symmetry reduction (P6${}_3$/mmc→P6${}_3$/mcm→P$\overline{6}$2m). The structures are discussed together with the coloring variants Y${}_{10}$RuCd${}_3$ and Y${}_9$CoMg${}_4$ on the basis of a group subgroup scheme. Striking features of the Lu${}_{20}$Ir${}_5$In${}_3$ structure are short Ir-Lu contacts and the structural segregation of In${}_3$ triangles (300 and 315 pm In-In) that are solely coordinated by lutetium atoms. Temperature dependent magnetic susceptibility studies of the Lu${}_{20}$Ir${}_5$In${}_3$ and Lu${}_{20}$Pt${}_5$In${}_3$ samples indicate Pauli paramagnetism. (© 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH)