In 1932, E. Zintl reported on the binary phase NaTl as the first example of a compound with formally negatively charged thallium, the so-called thallides. The formal electron transfer from the less electronegative metal sodium to the more electronegative thallium results in a diamondlike thallium substructure, which was interpreted in terms of the pseudo-element approach, introduced by W. Klemm. While located left to the so-called Zintl border between group 13 and group 14, introduced by F. Laves, text-book known NaTl is still referred to as the first Zintl phase and therefore set a milestone for the chemistry of Zintl compounds in general. NaTl can be prepared using classical high-temperature solid-state synthesis. At the same time, a stoichiometry range is given in the related binary phase diagram. In addition, E. Zintl himself also prepared NaTl in a low-temperature solution route by reducing thallium(I) iodide by sodium in liquid CrysAlisPro (version 171.43.105a) was used for data collection and data reduction. For the structure solution, ShelXT was used and the subsequent data refinement was carried out with ShelXL or olex2refine. Olex² was taken for visualization purposes and the software Diamond4 was chosen for the representation of the crystal structure. All atoms are depicted as ellipsoids with a 50% probability level.