Due to the fact, that the attempts to prepare binary RbTl did not succeed so far, we tried to approximate this compound by ternary approaches with potassium or cesium. Combinations of rubidium and potassium yielded in a homogeneity range of the the KTl structure type up to a rubidium proportion of 69% (see crystallographic data Table ) As side phase, K8-xRbxTl11 was always present, which also was reported for binary KTl. 9 These are built by two symmetry-independent thallium atoms located on special positions (Tl1 Wyckoff 16g, Tl2 Wyckoff 8f). In addition, alkali metals on three crystallographically independent, special sites (Wyckoff 8e, 8d, and 8f) are present (see Figure ).