Structural diversity in thallium chemistry

Structural Diversity in Thallium Chemistry. Part V

“…Whilst a rich diversity among chlorothallate(III) anions has previously been established [2 ± 9], less has been known with reference to bromothallate(III) anions, with most examples generally being limited to the [TlBr 4 ] À ion, and, to a lesser degree, the [TlBr 6 ] 3À ion [2]. Our recent efforts, however, have expanded this horizon, and, so far, we have reported the isolation of bromothallate(III) salts containing such diverse species as discrete [TlBr 5 ] 2À anions in both regular [1] [10] and highly distorted, axially stretched trigonal bipyramidal forms [11], cis-bromobridged chains composed of [TlBr 5 ] 2À units such that the Tl-atom is hexacoordinate [1], and mixed salts containing various combinations of unassociated anionic moieties like [TlBr 4 ] À Br À [1] [11], [TlBr 4 ] À [TlBr 6 ] 3À [1] [10], and [TlBr 4 ] À [TlBr 6 ] 3À 4 Br À [1].…”

“…Freshly prepared thallium(I) bromide was suspended in the appropriate solvent ( Table 1) and oxidized by warming with a slight excess of dibromine [17]. The bromothallate(III) complexes 1 ± 9 were conveniently prepared, as described previously [1] [10] [11], by adding an equimolar quantity of organic base to the TlBr 3 in the chosen solvent and then warming the mixture to dissolve any resulting precipitate. For crystal growth, various evaporation techniques were employed to minimize the rate of vapor diffusion and solvent loss so that well-formed crystals could be obtained.…”

1,4-Bis{[hydroxy(phenyl)phosphoryl]methyl}piperazine-1,4-diium tetrachloridocadmate(II) dihydrate and the cobaltate(II) analogue

“…The metal atoms adopt a distorted tetrahedral geometry, with M-Cl bond lengths ranging from 2.4110 (9) to 2.5314 (8) Å in (I), and from 2.2502 (16) to 2.3148 (18) Å in (II). The H 2 PBPA 2+ cations are located on crystallographic centres of inversion, with the piperazine rings in chair conformations; all bond lengths in these rings fall in the normal ranges (Linden et al, 1999). The P atoms show distorted tetrahedral geometry.…”

Crystal structure and phase transition in the compound [C6H5CH2NH(CH3)2]TlCl4

“…However a relatively small number of organic-cation thallium complexes has been characterized [5][6][7]. Thallium complexes exhibit a wide range of coordination numbers and geometries (tetrahedral [6,8,9], square pyramidal [9,10], trigonal bipyramid [5,8], octahedral [8,10] and the empirical formula of the complex is not always a reliable indicator for its structure. Some of these compounds exhibit structural phase transitions and interesting physical properties such as ferroelectricity and ionic conduction [11,12].…”