PREPARATION AND CRYSTAL-STRUCTURE OF K49TL108

K49Tl108 was prepared from the elements (molar ratio K: Tl = 1: 2) at 700 K. The crystal structure was determined by single crystal X-ray diffraction methods (a = 1728.7(1) pm, Pm 3, Z = 1, R = 0.086). It contains Tl12 icosahedra and Tl12 truncated tetrahedra (Kasper polyhedra). 20 truncated tetrahedra form Tl84-polyhedra (Samson polyhedra) by sharing hexagonal faces. These polyhedra are connected by common edges. Folded Tl3-chains connect the icosahedra and the Samson polyhedra to a framework. The truncated tetrahedra are occupied by potassium atoms.