Neue ternäre Kupferpnictide mit modifizierten BaAl4-Strukturen

New Ternary Copper Pnictides with Modified BaAl₄ Type Structures EuCu₂As₂ (a = 4.215(1) Å, c = 10.185(2) Å) and EuCu₂Sb₂ (a = 4.504(1) Å, c = 10.824(2) Å) were prepared by heating (900°C) mixtures of CuCl and arsenic (antimony) with europium. The by-products were dissolved by dilute acetic acid. The arsenide crystallizes in the ThCr₂Si₂ type structure (I4/mmm; Z = 2) with holes in the copper arrangement, whereas the antimonide forms the CaBe₂Ge₂ type structure (P4/nmm; Z = 2). The stability ranges of both phases were determined by mixed crystal formation in accordance with EuCu₂As_2–xSb_x. Magnetic measurements showed, that Europium is divalent and that the compounds order magnetically at low temperatures. BaCu₂Sb₂ (I4/mmm; a = 4.655(1) Å, c = 32.709(6) Å; Z = 6) was prepared by heating a mixture of binary antimonides of barium and copper in a melt of NaCl/KCl. The structure of this compound consists building elements of the CaBe₂Ge₂ and the ThCr₂Si₂ type structure. The already known compounds SrCu₂As₂ and BaCu₂As₂ were produced in a homogeneous form for the first time and their structures (ThCr₂Si₂ type) redetermined by means of single crystal X-ray methods.