Wallez Gilles, Jaulmes Sylvie, Elfakir Ammy, Souron Jean Paul, Quarton Michel
Laboratoire de Cristallochimie du Solide - Case 176, Université P. et M. Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France.
Acta Crystallogr C. 2004 Nov;60(Pt 11):i107-i109. doi: 10.1107/S0108270104022346. Epub 2004 Oct 22.
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) anions as their isotypic alkali counterparts.
硫酸二铊的室温形态β-Tl₂SO₄与β-K₂SO₄相似，其特征是存在孤立的硫酸根四面体以及两个不同的铊位点，配位数分别为9和11。除了一个氧原子外，所有原子都位于镜面上。尽管存在高浓度的Tl⁺阳离子，但6s²电子对的立体化学活性较低，这与同型的Tl₂XO₄化合物（X = Cr和Se）类似。这种行为是Tl-O键弱和X-O键强共同作用的结果，因为在Tl-O-X键中，O²⁻阴离子的电子云会强烈变形并向X偏移，导致在Tl原子一侧的负电荷较低。因此，孤对电子与O²⁻阴离子之间的库仑排斥力较弱。所有的Tl₂XO₄化合物都表现出与同型碱金属对应物相同的A⁺阳离子和[XO₄]²⁻阴离子的开放堆积结构。
