Na7RbTl4 has been prepared by solid state reaction from the elements. Single crystal X‐ray structure analysis suggested the presence of pseudo‐merohedral twinning. The final model could be derived in space group Pbam (a=16.3584(4) Å, b=16.3581(4) Å, c=11.3345(3) Å, V=3033.04(14) Å3, R1/wR2 0.0282/0.0402) and proved the presence of isolated [Tl4]8− anions, which are only known from two other solid state thallide phases so far. The structure of Na7RbTl4 is compared to the long‐known Na2Tl and the similarities and differences in the three‐dimensional arrangement within the crystal structures are reported on. DOS calculations revealed a pseudo‐band gap at EF. Dissolution experiments in the style of the chemistry of group 14 and group 15 Zintl anions in liquid ammonia yielded degradation of the thallides. Subsequent characterization of the reaction products by powder X‐ray diffraction allowed for the determination of alkali metal amide and elemental thallium as products.
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.
Two new ternary trielides Na7KTr4 (Tr=In, Tl) have been prepared by classical solid‐state reaction from the elements in tantalum ampoules. Both are isostructural to Na7RbTl4 and therefore crystallize in the orthorhombic space group Pbam (a=16.3202(3)/16.2860(6), b=16.3283(2)/16.2835(6), c=11.3094(2)/11.2771(4), V=3013.74(9)/2990.61(18), R1, wR2=0.0249, 0.0384/0.0447, 0.0608). The trielide subunit is built by two crystallographically independent [Tr4]8− tetrahedra. 23Na NMR as well as EPR spectroscopy was employed to characterize the compounds further. DOS calculations showed a (pseudo) band gap at EF for both compounds. Dissolution experiments in liquid ammonia were carried out for the two alkali metal indides Na7KIn4 and Na2In according to the chemistry of group 14 and 15 Zintl anions. After evaporating the solvent, the remaining material was analyzed by powder X‐ray diffraction and proved the formation of NaIn.
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