Single Crystal X‐Ray Structure Analyses of Binary and Ternary Compounds A₄₉Tl_108+x (A=K, Rb, Cs; x=0–1.76) Related to the K₄₉Tl₁₀₈ Type Structure

Abstract

The structural chemistry of alkali metal thallides shows a broad range of type structures. At an alkali metal : thallium proportion A : Tl 1 : 2 the perceived dependency on the alkali metal involved is conspicuous. Two main structure types are reported with A15Tl27 (A=K, Rb, Cs) and K49Tl108. The compound K49K108 with a 3‐dimensional Tl‐substructure has been known since 1993 from Cordier and Müller but so far only with potassium. We here present single crystal X‐Ray structure analyses of the compounds K49‐yRbyTl108, and K49‐yCsyTl108 (y<10) belonging to the K49Tl108 type structure. Additionally, structures of Rb49Tl109.67, Cs3.35Rb45.65Tl109.71 and Cs7.49Rb41.51Tl109.76 are introduced, which prove the possibility of Tl incorporation in the Tl12 icosahedra in K49Tl108 type structures. The effects of the change in alkali metals on the thallium substructure are discussed as well as the preferred Wyckoff sites of the different alkali metals.

[Tl7]7– Clusters in Mixed Alkali Metal Thallides Cs7.29K5.71Tl13 and Cs3.45K3.55Tl7

“…Alkali metal thallides can be described as materials at the frontier between ionic and intermetallic nature. , While a low amount of alkali metal of less than 50% results in the formation of rather metallic compounds, − increasing proportions lead to the formation of salt-like materials. The observed thallium subunits can then be well described by using the Zintl–Klemm formalism. − The first structurally characterized Zintl phase goes back to E. Zintl himself, who reported on the synthesis and characterization of textbook-known NaTl in the early 1930s .…”