The title compounds were prepared from the elements by reactions in sealed tantalum tubes in a high-frequency furnace. Their structures were re5ned from single crystal X-ray di4ractometer data: Pnma, a ؍ 744.4(1) pm, b ؍ 434.15(9) pm, c ؍ 845.5(1) pm, wR2 ؍ 0.0433, 658 F 2 values, 20 variables for EuRhIn, Fd3m, a ؍ 756.5(1) pm, wR2 ؍ 0.0349, 94 F 2 values, 5 variables for EuIr 2 , and Cmcm, a ؍ 434.78(3) pm, b ؍ 1124.0(1) pm, c ؍ 751.20(5) pm, wR2 ؍ 0.0561, 565 F 2 values, 16 variables for EuIrSn 2 . EuRhIn crystallizes with a TiNiSi type structure that consists of strongly puckered Rh 3 In hexagons.
The europium atoms 5ll the channels within the three-dimensional [RhIn] polyanion. EuRhIn orders ferromagnetically at 22.0(5) K with a saturation magnetic moment of 6.7(1) B /Eu at 4 K and 5.5 T. The divalent character of the europium atoms in EuRhIn was determined from temperature dependent susceptibility (7.9 B /Eu in the high-temperature part) and 151 Eu MoK ssbauer spectroscopic experiments. The latter show an isomer shift of ؍ ؊8.30(2) mm/s at 78 K. At 4.2 K full magnetic hyper5ne 5eld splitting subjected to signi5cant quadrupole splitting of E Q ؍ 8 mm/s is observed. EuRhIn is a metallic conductor with a room temperature value of 58 cm for the speci5c resistivity. The structure of the Laves phase EuIr 2 is con5rmed on the basis of single crystal X-ray data. The iridium atoms form a tetrahedral network with Ir+Ir distances of 268 pm. EuIrSn 2 adopts a MgCuAl 2 type structure that may be described as an iridium-5lled variant of a distorted CaIn 2 -like sublattice of composition EuSn 2 . The tin atoms in the distorted and puckered hexagonal network have shorter (303 and 322 pm) and longer (343 pm) tin-tin contacts.
1999 Academic press