Thallium i Compounds

Thallium(i) Compounds.—Isotopic exchange reactions between and Tl have been studied in a variety of solvents (H20-Et0H, H20-glycol, H2O-DMSO).  

Pulse-radiolysis of T -containing solutions, with conductivity and spectrophotometry being used as detection probes, provided evidence for the formation of TIOH , in equilibrium with 

Two groups of workers have shown that the chemical shift of the t1 ion is very dependent on the nature of the solvent. Thus, TP could be a useful probe of the function of univalent ions in biological systems. 

Tl derivatives of metal carbonyl anions are generally stable when the anion is weakly basic, e.g. Co(CO)3[P(OPh)3] , whereas disproportionation to Tl derivatives and Tl° occur when it is more strongly basic, e.g. Mn(CO)i.  

Hydrated TF -exchanged zeolite-X crystallizes in the cubic space group Fd3m. The TF ions are placed inside the sodalite cages in front of the hexagonal prisms 

Thallium(i) Compounds.—A comprehensive review of TF chemistry has been published by Lee.  

The bonding of T1+ ions in the zeolite lattice has been investigated by breadline 203JJ n.m.r. spectroscopy.  

Measurements of the low-frequency Raman spectrum of TIN3 at various temperatures are consistent with the existence of a low-temperature phase transition, involving distortion of the ion, at 225 K. Salicylato-(l,10-phenanthroline)thallium(i) exists in dimeric form with five-co-ordinate Tl. The phenanthroline is bidentate, with T1—N distances of 2.65 and 2.71 A, as is the salicylato ligand, although it is here markedly unsymmetrical (with Tl—O distances of 2.65, 2.98 A). Further, the former oxygen undergoes a weak bridging interaction with the second Tl atom of the dimer (Tl O = 3.00 A).  

Nuclear magnetic relaxation rates of in aqueous solution are markedly 

JiT-Ray photoelectron spectra of a number of Tl i -dicarbonyl compounds have been measured, showing that the influence of substituents on the binding energies of the T1 (4/5/2) electrons is second-order.  

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Thallo-. thallous, thalhum(I). -bromid, a, thallous bromide, thalliuro(I) bromide -chlorat, n. thallous chlorate, thallium(I) chlorate, -chlorid, n. thallous chloride, thallium I) chloride, -fluorid, n. thallous fiuoride. thal lium(I) fiuoride. -ion, n- thallous ion, thal lium(I) ion. -jodat, n. thallous iodate. thal liura(I) iodate. -jodid, n. thallous iodide. thallium(I) iodide, -salz, n. thallous salt. thallium(I) salt, -sulfat, n. thallous aulfate. thailium(I) sulfate, -verbindung, /. thallous compound, thallium(I) compound. 

Group 13/III is the first group of the p block. Its members have an ns np1 electron configuration (Table 14.5), and so we expect a maximum oxidation number of +3. The oxidation numbers of B and A1 are +3 in almost all their compounds. However, the heavier elements in the group are more likely to keep their s-electrons (the inert-pair effect, Section 1.19) so the oxidation number +1 becomes increasingly important down the group, and thallium(I) compounds are as common as... 

Organoelemental thallium(I) compounds were prepared by similar routes starting with thallium(I) cydopentadienide, for instance [Eq. (4)]. In contrast to the clusters described so far, the metal-metal interactions in the tetrahedral dusters of compound 19 [42] or of the related pyrazolato derivative 20 [43] (Figure 2.3-4) are quite weak their bonding situation and stability are discussed in Section 2.3.3.1.2. 

Thallium(I) Compounds. Carboxylic anhydrides can be prepared by the reaction of acyl or aroyl halides in ether with thallium(I) carboxylates (26) ... 

Concerning the structure of the pentachlorocyclopentadienyl-substituted thallium(I) compound LHIm it has been suggested that in the solid state the thallium cation nestles in the C5CI5 anion and that some charge is transferred from the anion to the empty thallium orbital (177), a situation typical for an ion pair with a low degree of covalent interaction. 

The monovalent thallium ion, with its relatively large ionic radius (1.50 A for a 6-coordinate ion), has only weak electrostatic interactions with its ligands. The valence-shell electronic configuration of d s with a lone pair makes the covalent interactions weak as well. Overall, the thallium ion is weakly solvated in most solvents, and crystallizes even without any coordinated solvent molecules. Thallium(I) compounds are the most widely explored group among thallium derivatives. The T1+ state is also the most stable ion in aqueous solutions. 

Thallium (10 % of earth s crust) is recovered principally from the flue dust of pyrites burners. The soft, grey metal, which has a hexagonal close-packed structure, is rather more reactive than gallium and indium because of the ease with which it forms a unipositive ion. It oxidises in moist air, decomposes steam at red heat and dissolves readily to form thallium(I) compounds in dilute mineral acids other than HCl, because of the insolubility of TlCl. 

Thallium (Tl, at. mass 204.37) occurs in its compounds in the I and III oxidation states. Thallium(I) compounds are the more stable. Thallium(I) forms sparingly soluble compounds, white TlCl, yellow Til, and black TI2S, as well as thiosulphate and ammine complexes of low stability. Colourless Tl ions can exist only in strongly aeidic media since the brown hydroxide, Tl(OH)3, which has no amphoteric properties, is precipitated at pH values as low as 0.3. Thallium(ni) yields halide-, oxalate-, and tartrate complexes. T1(I) is oxidized to Tl(ni) only by powerful oxidants, e.g., Mn04 , aqueous Cl2, and aqueous Br2. 

Several attempts have been made to replace silver ion with ions of other elements [74, 75]. Of particular practical and theoretical interest is the possibility of using thallium salts [74]. The physical and chemical properties of silver(I) and thallium(I) compounds are similar. Thallium(I) salts are stable up to 150°C in the absence of oxygen, but thallium(I) complexes with unsaturated hydrocarbons have not been studied before. The results of the separation are given in Table 6.1 [74]. 

Not only is it not possible to determine the oxidation number of a given element from the I values of inner sheUs unless comparison is made with other compounds containing analogous hgands, but in the meantime three cases of anti-stone-age behaviour have been noted TI2O3 has lower I than all measured thallium(I) compounds and Pb02 lower I than all measured lead(II) compounds 136) and generally co-balt(III) has lower I than cobalt(II) 137). 

Thallium(I) compound C-Alkylation with cyclic sulfonium salts... 

There are a few examples in the literature of the application of thallium(i) compounds as acid catalysts, thallium(i) acetate and thallium(i) carbonate were used to produce polyethylene terephthalate (PET) by initial transesterification of dimethyl terephthalate with ethylene glycol to form diethylene glycol terephthalate, which then polymerised to give a spinnable material (Scheme 20.21). According to the authors, the use of thallium compounds as catalyst improves the thermal stability and photochemical resistance of the formed polymer. 

Tr and K+ have similar sizes they both form soluble carbonates and hydroxides. Thallium(I) compounds are very poisonous. 

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