The asymmetric unit of (I) consists of each six symmetry-independent thallium positions and alkali metal positions, while in (II) there are nine symmetry-independent thallium and alkali metal positions, which are all located on a general Wyckoff position 8f. The compressed octahedra in the two new compounds are similar to those in CsTl 10 , in the solid solution K1-xRbxTl, Cs7.29K5.71Tl13 , A10Tl6O2(A=K, Rb) , Cs10Tl6TtO4 (Tt=Si, Ge) and Cs10Tl6SnO3 53 (see table with distances and distortion degree in SI chapter 5). in a distorted α-uranium packing. This is similar to KTl, whereas the clusters in CsTl pack in ADD'D'' layers, which is according to a distorted γ-plutonium packing (Figure ). All hexathallide octahedra are each surrounded by 20 alkali metal atoms (d(Tl-A)≤4.7 Å), six of them are exo-coordinating to each vertex of the octahedron. Additionally, there are four face capping and ten edge capping alkali metal atoms (see Figure and SI).