Thallium chloride exchange

The first extensive study of ligand exchange on thallium(III) complexes comprised mutual chloride exchange between the various T1C1 " (n = 1-4) complexes, as well as between the thallium chloro complexes and the free chloride ion in aqueous solution containing... 

Far more surprising was the fact that the anation reactions constituted only a minor part of the chloride exchange in this chemical system. Instead, up to the Cl/Tl ratio 3, the dynamics is dominated by a direct ligand exchange between two thallium complexes. 

For the direct exchange between the thallium complexes, Eq. (9), the dissociatively activated reaction mechanism previously proposed for the thallium chloride system (169) could now be confirmed and... 

All the exchange reactions in aqueous medium are reversible, but they do not allow preparation of pyrochlores with large amounts of A ion the exchange of in Hi + jM20g-H20 for monovalent cations such as Na" or is not quantitative for X > 0. A solid-state exchange reaction between the alkali chlorides and the thallium pyrochlores has been developed, based on the volatility of thallium chloride, which allows the synthesis of sodium- and potassium-rich pyrochlores ... 

The utility of thallium(III) salts as oxidants for nonaromatic unsaturated systems is a consequence of the thermal and solvolytic instability of mono-alkylthallium(III) compounds, which in turn is apparently dependent on two major factors, namely, the nature of the associated anion and the structure of the alkyl group. Compounds in which the anion is a good bidentate ligand are moderately stable, for example, alkylthallium dicar-boxylates 74, 75) or bis dithiocarbamates (76). Alkylthallium dihalides, on the other hand, are extremely unstable and generally decompose instantly. Methylthallium diacetate, for example, can readily be prepared by the exchange reaction shown in Eq. (11) it is reasonably stable in the solid state, but decomposes slowly in solution and rapidly on being heated [Eq. (23)]. Treatment with chloride ion results in the immediate formation of methyl chloride and thallium(I) chloride [Eq. (24)] (55). These facts can be accommodated on the basis that the dicarboxylates are dimeric while the... 

Reaction of the anion 21 with Cp or Cp metal fragments provides further metallocene-type complexes with a pendant phosphaferrocene side-chain. For example, the reaction of the thallium derivative T1 21 with [Cp RhCl2]2 yields the cationic pentamethylrhodocenium 24 as its chloride (Scheme 1.5.10). This is an interesting species because it is a chiral water-soluble P ligand. The chloride anion can be exchanged by PF,s to make the compound more soluble in organic solvents. 

Fig. 1. Simultaneous separation and detection of anions and cations on a latex agglomerate column. Column Dionex HPIC-CS5 cation exchange column (250X2 mm) with precolumn HPIC-CG5 (50 X 4 mm) eluent 0.5 mM copper sulfate, pH 5. 62 flow rate 0.5 ml/min sample volume 20 gl containing 0.1 m M of each ion detection two potentiomet-ric detectors equipped with different ion-selective electrodes in series. Peaks (1) chloroacetate, (2) chloride, (3) nitrite, (4) benzoate, (5) cyanate, (6) bromide, (7) nitrate, (8) sodium, (9) ammonium, (10) potassium, (11) rubidium, (12) cesium, (13) thallium. Reprinted with permission from [10].

A better route is the one shown in Scheme 11. The benzene complex 104 forms readily in near quantitative yield upon heating Ru(III) chloride and 1,3-or 1,4-cyclohexadiene in EtOH. The introduction of the Cp ligand is by hali-de/Mcp exchange. The classic procedure to 105 required a stoichiometric quantity of thallium or silver [103], but a very recent, improved procedure shows that cyclopentadiene/K2C03/ abs. EtOH can be used successfully [104]. Although beyond the scope of this review, it is interesting to note that the much less electrophilic complexes [(arene)Ru(C5Me5)] [PFg] are accessible in a one-pot procedure from RuClj [105]. The sequence Birch reduction/complexa-... 

The properties of anion-exchange resins of several types have been described in detail by Kraus and Nelson 351-356) and others (557, 358). Selenium(IV), tellurium(IV), and arsenic(III) and (V) can be extracted from a variety of media 359-361). Thallium(III) and antimony(V) can be separated using the iodide and chloride forms of Dowex-1 (5(52, 363). Beryllium(II) was efficiently extracted by the carbonate form 364, 365) and chromium(III) and lead(II) by the phosphate form of AV-17 resin 366). Zinc(II) can be removed from a solution containing several metals (5(57, 368) and silver in concentrations at the 0.04-ppb level can be extracted from seawater (5(59). Cobalt(II), zinc(II), antimony(III), silver(I), and iron(III) ions have also been extracted from spiked seawater samples by anion exchange even though the actual form of the ions in the aged solution was uncertain (570). Anion resins have been modified with Trilon B (577) and with a-hydroxyisobutyronitrile (572) to increase the extraction of several trace-metal pollutants. Amberlite IRA 400 treated with the sulfonic acid derivative of dithizone can be used to concentrate heavy metals (575). 

In the case of thallium(III) the quadrupolar relaxation in the predominant chloride complex determines the line width over the whole temperature range studied and only lower limits of the exchange rate could be obtained ... 

Considerable further contributions to the understanding of the chemistry of nitrosyl chloride solutions have been provided by the results of tracer studies o- using 36C1. The exchange was studied between nitrosyl chloride and the dissolved chlorides of aluminium(III), gallium(III), indium(III), thallium (III), iron(III) and antimony(V). Rapid exchange was found and it was concluded that the chlorine... 

Thallium(ii) has been generated in the pulse radiolysis of TF and in IM-HC104. The rates of the reaction of TF + OH and TF + H have been measured, and from data on the Fe TF reaction, the free energy of formation of TF has been shown to be 42 kcal mol. TF plays no part in the TF-TF exchange. Three chloride complexes of TF have also been characterized by radiolytic techniques. Absorption spectra for TICF, TICI2, and TlCls" have been reported. In the complex formation reaction... 

Metalation-demetalation sequences have been invoked to account for palladium(u) chloride-catalysed allylic and enol ester exchange, and organomercury(ii) and bis(organo)thallium(iii) ion catalysis of the hydrolysis of isopropenyl acetate. 

Activation. KIO clay may be used crude, or after simple thermal activation. Its acidic properties are boosted by cation exchange (i.e. by iron(III) or zinc(II) ) or by deposition of Lewis acids, such as zinc(II) or iron(III) chloride (i.e. clayzic and clayfec ). In addition, KIO is a support of choice for reacting salts, for example nitrates of thallium(III), iron(III) ( clayfen ), or copper(II) ( claycop ). Multifarious modifications (with a commensurate number of brand names) result in a surprisingly wide range of applications coupled with the frequent imprecise identification of the clay (KIO or one of its possible substitutes mentioned above), they turn KIO into a Proteus impossible to grab and to trace exhaustively in the literature. 

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