superstructures: RuIn with = Sc, Y, Dy-Tm and Lu.

The rare earth-rich intermetallic phases RuIn with = Sc, Y, Dy-Tm and Lu were synthesized by reactions of the elements in sealed tantalum ampoules in an induction furnace. The samples were characterized through Guinier powder patterns and the structures of ScRuIn and ErRuIn were refined from single crystal X-ray diffraction data. The indides crystallize with the PtZnCd type space group 4/. The RuIn phases are superstructures of the packing and can be explained as intergrowth variants of tetragonally distorted, CsCl derived slabs of compositions Ru and In. Chemical bonding is discussed for ScRuIn and ScRuMg in comparison with the binaries ScRu, ScMg and ScIn. The Ru/Mg respectively Ru/In ordering leads to an increase of Sc-Sc bonding for the slab with the shorter Sc-Sc distances, while the Sc-Ru bond strength values remain similar. The strongest bonding interactions occur within the magnesium and indium square nets. Magnetic susceptibility measurements reveal Pauli paramagnetism for LuRuIn while DyRuIn, HoRuIn, ErRuIn and TmRuIn are Curie-Weiss paramagnets. Antiferromagnetic ordering occurs at 13.1, 5.3 and 2.9 K for DyRuIn, ErRuIn and TmRuIn, respectively. DyRuIn and ErRuIn show metamagnetic transitions at critical fields of 4.6 and 3.2 T.