Gold-thallium complexes

An example of this is the gold-thallium complex n[Au(CN)2] [69], prepared by reaction of T1N03 and K[Au(CN)2]-2H20 in the 90s by Patterson et al. This group carried out a pioneering study of the luminescence properties of this complex and their theoretical interpretation. The structure showed a complexity that made the analyses difficult. Thus, neutron diffraction studies showed thallium-gold interactions of 3.446 and 3.463 A, shorter than the sum of their van der Waals radii (3.62 A) in one of the three crystallographically-distinct Au sites in the crystal. 

Although there are luminescent gold-thallium complexes of different nuclearity, in this part we deal only with polymeric species containing Au-Tl contacts. Such complexes have been prepared following two different strategies ... 

A. Supramolecular Gold-Thallium Complexes with Bidentate Ligands... 

Thallium(i) Derivatives of Nickel, Palladium, Platinum, and Gold Coordination Complexes 395... 

Table 14 Palladium, platinum, and gold coordination complexes that bind thallium...

The first descriptions of heteronuclear luminescent supramolecular complexes were given by Fackler et al. in 1988 and 1989. In these studies, one gold-thallium and one gold-lead complex were reported. As in the case of the gold-silver dinuclear systems, the extended systems appeared as a result of the unidirectional polymerization of dinuclear or trinuclear units through metal-metal interactions. These were prepared by reaction of the gold precursor [PPN][Au(MTP)2] (PPN = N(PPh3)2 ... 

The complexes exhibited different behavior in solution. The gold-thallium derivative showed a shift of the emission to 536 nm when the measurement was carried out in frozen solution. This was explained by a higher aggregation of [Aull(MTP)2] units in the solid state compared to the situation in solution. In the case of the Au-Pb compound, the emission spectrum showed a strong dependence on the aggregation state and temperature. Thus, the emission band in TH F solution, which appeared at 555 nm (298 K) (x = 57 ns), was shifted to 480 nm in frozen solution (x = 2.3 ps) or appeared at 752 nm in solid state (x = 22 ns). As with the thallium complex, the shift to high energy in solution may have been related to the polymeric structure of the complex in the solid state that was not reproduced in solution. 

As described above, among the several closed-shell metal ions that form luminescent supramolecular entities with gold, thallium(I) forms the most numerous examples. While aurophilic attractions can be considered the upper extreme of the metallophilic interactions (with values up to 46 kJ mol-1), intermetallic contacts involving T1(I) centers appear as the weakest ones (even <20 kJ mol-1),46 which is explained by the enhancement of the Au---Au interactions and the weakening of the Van der Waals attractions between the s2 metal atoms produced by the relativistic effects.47 Nevertheless, the complexes in which this interaction appears are surprisingly stable, with additional electrostatic, packing forces, or the ligand architecture, responsible for this fact. 

Reactions between basic gold(I) complexes and acid thalliumff) salts, which give rise to supramolecular networks formed via acid-base stacking containing unsupported gold-thallium interactions. 

C6C15) with dimethylsulfoxide (DMSO), which leads to the synthesis of [Tl2 Au(C6F5)2 2 p-DMSO 3] or [Tl2 Au(C6Cl5)2 2 h-DMSO 2]ra, respectively.62 The crystal structure of the complex with fluorine shows a monodimensional polymer formed by repetition of [Au--Tl(p-0 = SMe2)3Tl] units, with gold-thallium interactions of 3.2225(6)-3.5182(8), while the pentachlorophenyl derivative contains two bridging DMSO molecules and an additional [Au(C6Cl5)2] anion. In addition, a thallium-thallium interaction of 3.7562(6) A appears in the latter (Fig. 21). 

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