β-Tl₂SO₄

Abstract

The ambient-temperature form of dithallium sulfate, beta-Tl(2)SO(4), is similar to beta-K(2)SO(4) and is characterized by isolated sulfate tetrahedra and two different thallium sites with coordination numbers 9 and 11. All the atoms, except one O atom, lie on mirror planes. In spite of there being a high concentration of Tl(+) cations, the stereochemical activity of the 6s(2) pairs is low, similar to that of isotypic Tl(2)XO(4) compounds (X = Cr and Se). This behaviour is the consequence of both weak Tl-O bonds and strong X-O bonds, because in a Tl-O-X linkage the electronic cloud of the O(2-) anion is strongly distorted and displaced towards X, resulting in a low negative charge in the face of the Tl atom. Consequently, the Coulombic repulsions between the lone pair and the O(2-) anions are weak. All of the Tl(2)XO(4) compounds exhibit the same open packing of A(+) cations and [XO(4)](2-) anions as their isotypic alkali counterparts.

Reactions of [SiF4(NH3)2] with Fluorides AF (A = Li–Cs, Tl, NH4) in Liquid NH3: A [NH4(NH3)2]+ Cation and a Thallophilic Interaction in [Tl2(NH3)6]2+

“…For that, see the quantum-chemical part of the manuscript below. Such a Tl­(I)···Tl­(I) distance shorter than 4 Å has also been observed in β-Tl 2 SO 4 with 3.9141(6) Å . Two symmetry-equivalent [Tl­(NH 3 ) 3 ] + cations are shown in Figure .…”

“…Such a Tl(I)•••Tl(I) distance shorter than 4 Å has also been observed in β-Tl 2 SO 4 with 3.9141(6) Å. 17 The next-nearest F atoms of [SiF 6 ] 2− anions are 3.2454(18) Å away from the Tl cations, and the overall coordination sphere of the Tl + cation is best described with coordination number (CN) = 3 + 2 + 1 for the three ammine ligands, the two F atoms, and the other Tl + cation, respectively. See Figure 9 for an illustration.…”