The Crystal Structures of Eu 5 Ge 3 and EuIrGe 2

Eu 5 Ge 3 and EuIrGe 2 were prepared from the elements in tantalum tubes, and their crystal structures were determined from single crystal X‐ray data. Eu 5 Ge 3 adopts the structure of Cr 5 B 3 : I4/mcm, a = 799.0(1)pm, c = 1 536.7(1)pm, Z = 4, w R2 = 0.0421 for 669 F 2 values and 16 variables. The structure of Eu 5 Ge 3 contains isolated germanium atoms and germanium atom pairs with a GeGe distance of 256.0 pm. Eu 5 Ge 3 may be described as a Zintl phase with the formulation [5 Eu 2+ ] 10+ [Ge] 4− [Ge 2 ] 6− . Magnetic investigations of Eu 5 Ge 3 show Curie‐Weiss behaviour above 50 K with a magnetic moment of μ exp = 7.6(1) μ B which is close to the free ion value of μ eff = 7.94 μ B for Eu 2+ . EuIrGe 2 is isotypic with CeNiSi 2 : Cmcm, a = 445.5(2) pm, b = 1 737.4(4) pm, c = 426.6(1) pm, Z = 4, w R2 = 0.0507 for 295 F 2 values and 18 variables. The structure of EuIrGe 2 is an intergrowth of ThCr 2 Si 2 ‐like slabs with composition EuIr 2 Ge 2 and AlB 2 ‐like slabs with composition EuGe 2 in an AB stacking sequence. Both slabs are distorted when compared to the symmetry of the prototypes. The GeGe distance of 256.6 pm in the AlB 2 ‐like fragment is comparable to that in Eu 5 Ge 3 .