Structural diversity in thallium chemistry

Structural Diversity in Thallium Chemistry. Part V

“…The combination of microanalytical and Raman-spectroscopic measurements conducted on the remaining solid-state mono-and disubstituted pyridinium bromothallate(III) salts, 5 ± 9, established that the structures all contained tetrabromothallate(III) ions, and these complexes have the [BaseH] ¥ [TlBr 4 ] À stoichiometry ( Table 1). The TlÀBr stretching frequencies observed for these complexes ( Table 5) are very similar to those obtained for salts known to possess the tetrahedral [TlBr 4 ] À species [10] [11] [34]. Since the Raman spectra showed clearly that these complexes contained undistorted [TlBr 4 ] À anions, further analyses by means of X-ray crystallographic studies were not undertaken.…”

“…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].…”

“…Consequently, thermoanalytical methods might elicit whether analogous phase changes occur in recognized mixed salts such as the 1,1,3,3-tetramethylimidazolidinium derivative [10]. As the factors that govern a particular bromothallate(III) structure and stereochemistry are still being elucidated, investigations regarding these systems are ongoing.…”

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

“…An ortep drawing of the asymmetric unit of the N-N dimethyl benzylammonium tetrachlorothallate (III) is shown in figure 1. Organic group C1 -N : 1.494(7) C1 -N -C2 : 110.8(5) N -C2 : 1.468 (7) C2 -N -C3 : 112.5(5) N -C3 : 1.509 (6) C1 -N -C3 : 111.0(5) C3 -C4 : 1.508 (7) C4 -C3 -N : 112.9(4) C4 -C5 : 1.386 (8) C5 -C4 -C9 : 120. The structure consists of inorganic layers alternating with organic sheets which are both perpendicular to the b axis (Fig.…”

“…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].…”