Eu₄OCl₆ and Eu₄OBr₆: Crystal growth and structure

Abstract

Abstract Faint yellow transparent single crystals of Eu 4 OCl 6 (1) and Eu 4 OBr 6 (2) grow from fluxes that emerge from reaction mixtures containing EuX 3 (X  Cl, br), Eu 2 O 3 and lithium metal in 6:1:8 molar ratios at elevated temperatures in tantalum ampoules. Both crystallize with the Ba 4 OCl 6 type structure (hexagonal, P6 3 mc, Z = 2, 1: a = 944.07(4), c = 715.60(4) pm and 2: a = 982.04(4), c = 749.69(5) pm) with „isolated”︁ O 2− centered Eu 4 tetrahedra.