Thallium chemistry

The volatility of the reactants is a concern in some solid state syntheses. This may be a slight problem in bismuth cuprates synthesized at high temperatures because Bi2Os has an appreciable vapor pressure at these temperatures (i.e. 900-950°C) however, chemical analyses of samples of bismuth-based superconductors before and after reactions at temperatures up to 900°C indicate no detectable loss of bismuth. This problem is much more severe in the case of thallium chemistry. 

Thallium chemistry was divided into two independent fields nine years after the discovery of the element, with the first preparation of diethylthallium chloride. Organothallium chemistry thus became an independent and fruitful counterpart to the inorganic chemistry of this element see Thallium OrganometaUic Chemistry). 

The Tl -Tl relationship is therefore a dominant feature of thallium chemistry. The standard reduction potentials at 25 °C and unit activity of H+ are TIVtI = —0.336 V, T1 /T1 = +0.72 V, and Tl /Tli = +1.25V. Estimates have also been made for the couples T1 /T1 = +0.33 V and Tl /Tl = 2.22 V. The generally valid limitations concerning the use of standard electrode potentials to predict the redox chemistry of real systems are especially important in the case of thallium factors such as complex formation in the presence of coordinating anions or neutral ligands and pH dependence due to hydrolysis do affect the actual or formal redox potentials. For example, redox potentials have been measmed for TICI/TICI3 =+0.77 V in IM HCl and T10H/T1(0H)3 = —0.05 V in alkaline soluhon. These formal potentials differ from the standard value for Tiin/Tii = +1.25 V. The difference can be attributed to the substanhal difference between the complex forming abilities of Tl and Tl , which will be discussed in detail later. The... 

Most of the compounds discussed contain boron, although studies involving A1 and Ga have increased. Little indium and thallium chemistry is known, presumably owing to the rarity of the former and the toxicity of the latter. This... 

In this review, primarily the developments in thallium coordination chemistry since the early 1980s will be surveyed. CCC (1987) is an excellent reference source for work prior to that time. In general, organometallic compounds are outside the scope of this article. There are several useful review and reference articles that describe thallium chemistry, including organothallium work. " " " Thallium is an important element in the field of high-temperature superconducting materials." ... 

An interesting alternative which combines both boron and thallium chemistry has been developed. The arylthallium compound is treated with diborane to provide the arylboronic acid which, by oxidation under standard conditions, yields the phenolic compound in good yield (equations 58 and 59)". ... 

Except for these three topics, thallium chemistry has been explored much less than that of most elements. During the last three decades... 

The increasing interest in thallium chemistry is due to several distinct applications. Besides the above-mentioned redox properties used in organic preparative chemistry and for model studies of electron transfer reactions, it can be perceived that thallium has found applications as a model for the general behavior of metal ions. For example, Tr is of particular interest because of its importance as a probe for the role of alkali metal ions. The ionic radius of TL, rxl. = 1.47 A, is only slightly larger than ky. = 1.33 A, and approximately the same as rRb+ = 1.47 A (34). Because of the ease with which Tl can be monitored by spectroscopic (35, 36), fluorescence (57), polarographic... 

Relatively little work has been published in the area of organo-thallium chemistry this year. Vinyl ketones have been shown to undergo efficient arylation, leading to B-aryl ketones, when treated... 

This area has been slightly more active in 1992 than the previous year, with approximately 15% of the references collected being devoted to thallium chemistry. 

Linden, A., Petridis, A. and James, B.D., Structural diversity in thallium chemistry. IV Further exanples of solid state bromothallate(lll) derivatives obtained by enploying certain classes of allq l diammonium cations, Inorg. Chim. Acta 332, 61-71 (2002). 

Recall from the discussion in Chapter 12 (pp. 310-311) that these half-reactions do not stand alone but rather must be measured versus another half-reaction such as the standard hydrogen electrode. (See Problems 14.24—14.26 for additional insight into the utility of the standard reduction potentials in thallium chemistry.)... 

In summary, the chemistry of Group 3A oxides, hydroxides, and halides traces a progression from the unique metalloid boron, whose compounds are typically covalent, down to the rather typical metals, aluminum to thallium. At the top of the group, the + 3 oxidation state is predominant, but toward the bottom, the -I-1 state becomes more stable until it predominates in thallium chemistry. 

Some articles in journals discuss new thallium chemistry [22] aqueous... 

The format of this year s report follows that established last year. Aspects of the organic applications of the five elements are covered elsewhere, and are again omitted from this survey. Overall, reports on boron are up while those on the middle triad of elements are down, largely due to a diminution of interest in the chemistry of oligomeric 13-15 compounds. Activity in the area of thallium chemistry has remained flat, generating less than a quarter of the reports of any of the elements A1 to In and an order a magnitude lower than those for boron. 

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