Die Europium(II)-Oxidhalogenide Eu2OBr2 und Eu2OI2

Abstract

Abstract The syntheses and crystal structures of the two isotypic europium(II) oxide halides Eu2OBr2 and Eu2OI2 are reported. They crystallize orthorhombically in the space group Ibam (Z=4; Eu2OBr2: a=709.86(5), b=1200.34(9), c=628.71(4) pm; Eu2OI2: a=739.78(5), b=1295.13(9), c=644.82(4) pm). The unit cell parameters presented here, and thus the interatomic distances of Eu2OI2, are significantly smaller than the ones reported in the literature, which is explained by the substitution of europium with larger barium cations due to the synthesis route described in the early study. Central building blocks of both crystal structures are trans-edge-connected [OEu4]6+ tetrahedra forming straight ∞ 1 { [ OEu 4/2 e ] 2 + } $_\infty ^1\{ {[{\text{OEu}}_{{\text{4/2}}}^{\text{e}}]^{2 + }}\} $ chains running parallel to the [001] direction. Bundled like a hexagonal rod packing, their interaction is achieved by Br− or I− anions for charge compensation.