Abstract Yellow prismatic crystals of rubidium bromido-antimonate(III) Rb7Sb3Br16 and of two different modifications of thallium bromido-bismuthate(III) Tl7Bi3Br16 were obtained by solvent-free synthesis and by precipitation from acidic aqueous solutions. X-ray diffraction analyses revealed the Tl7Bi3I16-type for α-Tl7Bi3Br16 (orthorhombic, Cmcm, a = 2324.31(8) pm, b = 1346.69(4) pm, c = 3460.0(1) pm; Pearson symbol oC312) and a new structure type for β-Tl7Bi3Br16 (monoclinic, C2/c, a = 2331.87(5) pm, b = 1343.33(3) pm, c = 3546.01(7) pm, β = 102.708(1)°; mC312). The antimonate Rb7Sb3Br16 adopts the Tl7Bi3I16-type, too (orthorhombic, Cmcm, a = 2347.16(3) pm, b = 1357.89(5) pm, c = 3539.47(9) pm; oC312). The crystal structures of α- and β-Tl7Bi3Br16 comprise alternating slabs of isolated [BiBr6]3– octahedra and [Bi2Br10]4– octahedra pairs. Both structure types are hierarchically organized and can be regarded as sphere close packing with the same stacking sequence, if octahedra and octahedra pairs are replaced by spheres of equal size. The structural relationship between the Tl7Bi3I16-type and the hydrate Na7Bi3Br16 · 18H2O, which comprises similar structural features, is discussed.

中文翻译：

---

α-Rb7Sb3Br16、α-和β-Tl7Bi3Br16的晶体结构及其与球体密堆积的关系

摘要 通过无溶剂合成和从酸性水溶液中沉淀得到溴化锑酸铷 (III) Rb7Sb3Br16 和溴化铋酸铊 (III) Tl7Bi3Br16 的两种不同变体的黄色棱柱晶体。X 射线衍射分析揭示了 α-Tl7Bi3Br16 的 Tl7Bi3I16 型（正交，Cmcm，a = 2324.31(8) pm，b = 1346.69(4) pm，c = 3460.0(1) pm；Pearson 符号 oC312） β-Tl7Bi3Br16 的结构类型（单斜晶系，C2/c，a = 2331.87(5) pm，b = 1343.33(3) pm，c = 3546.01(7) pm，β = 102.708(1)°；mC312）。锑酸盐 Rb7Sb3Br16 也采用 Tl7Bi3I16 型（斜方晶系，Cmcm，a = 2347.16(3) pm，b = 1357.89(5) pm，c = 3539.47(9) pm；oC312）。α-和β-Tl7Bi3Br16 的晶体结构由孤立的[BiBr6]3-八面体和[Bi2Br10]4-八面体对的交替板片组成。如果八面体和八面体对被相同大小的球体代替，两种结构类型都是分层组织的，并且可以被视为具有相同堆叠顺序的球体紧密堆积。讨论了Tl7Bi3I16型与具有相似结构特征的水合物Na7Bi3Br16·18H2O之间的结构关系。