Boron and Thallium

Boron and Thallium.—The lithium salts of orr/io-carboranes, o-RCBieHi CLi (R = Me or Ph), react with hexafluorobenzene to give only the 1,4-di-o-carboranyl derivatives, even with a deficiency of hexafluorobenzene.  

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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)". ... 

Cleavage by a j8-diketone of hydrocarbyl groups from metal alkyls is a useful and potentially general synthetic route that has, thus far, been applied to prepare diketonates of boron - and thallium(III). ° In both cases, only one alkyl group is cleaved and chelates of the type (diketonate) MR2 (M = B, Tl) result. Cleavage of both methylcyclopentadienyl groups from Sn(MeC5H4)2 by... 

The metals that are suitable as color producers in flames are mainly found in the first two columns of the periodic system—lithium (red), sodium (yellow), potassium (violet), rubidium (red), cesium (blue), calcium (orange-red), strontium (red), barium (green), radium (red), and copper (blue or green). To these might be added boron and thallium (both green) and the weak color producers zinc (bluish white), indium (pale blue), and tellurium (greenish). 

Only thallium of the Group III elements is affected by air at room temperature and thalliumflll) oxide is slowly formed. All the elements, however, burn in air when strongly heated and, with the exception of gallium, form the oxide M2O3 gallium forms a mixed oxide of composition GaO. In addition to oxide formation, boron and aluminium react at high temperature with the nitrogen in the air to form nitrides (BN and AIN). 

A. N. Nesmeyanov and R. A. SokoUk, The Organic Compounds of Boron, Aluminum, Gallium, Indium and Thallium, North-HoUand Publishing Co., Amsterdam, the Netherlands, 1967. 

Almond, M. J. Group 13 boron, aluminum, gallium, indium and thallium. J. Organomet. Chem. 2002, 30, 128-158. 

This section will focus on homonuclear neutral or anionic clusters of the elements aluminum, gallium, indium, and thallium, which have an equal number of cluster atoms and substituents. Thus, they may clearly be distinguished from the metalloid clusters described below, which in some cases have structures closely related to the allotropes of the elements and in which the number of the cluster atoms exceeds the number of substituents. The compounds described here possess only a single non-centered shell of metal atoms. With few exceptions, their structures resemble those of the well-known deltahedral boron compounds such as B4(CMe3)4 [30], B9CI9 [31] or [B H ]2 [32]. The oxidation numbers of the elements in these... 

Homonuclear clusters of the heavier elements of the third main-group aluminum, gallium, indium and thallium having direct element-element interactions form a fascinating new class of compounds. As discussed in the previous Chapter 2.3, in some cases their structures resemble those known with the lightest element of that group, boron, while in other cases novel, metal-rich compounds were obtained which do not have any analogue in boron chemistry. 

Al, Ga, In and T1 differ sharply from boron. They have greater chemical reactivity at lower temperatures, well-defined cationic chemistry in aqueous solutions they do not form numerous volatile hydrides and cluster compounds as boron. Aluminium readily oxidizes in air, but bulk samples of the metal form a coherent protective oxide film preventing appreciable reaction aluminium dissolves in dilute mineral acids, but it is passivated by concentrated HN03. It reacts with aqueous NaOH, while gallium, indium and thallium dissolve in most acids. 

The boron group (group 13 IIIA) consists of the elements boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Ti). All have three electrons in their outer valence shell. A few exhibit metal-like characteristics by losing one or more of their outer electrons. For example, aluminum can lose one or three of its valence electrons and become a positive ion just as do other metals, but other elements in this group have characteristics more hke metalloids or semiconductors. 

A. The Oxide Fluorides of Boron, Aluminium, Gallium, Indium, and Thallium... 

Boron, aluminum, gallium, indium, and thallium are members of group 13 of the Periodic Table. Some important properties of these elements are given in Table 13.1.1. 

Carboranyl derivatives of mercury and thallium as synthons for boron-substituted carboranes 91PAC357. 

Of the elements in Group Illb, only boron and aluminum will be discussed here. Descriptions of the rarer metals of the group, gallium, indium and thallium, as wrell as those for the entire Ilia group and the rare-earth metals, appear in more specialized works. 

The elements below boron in Group IIIA of the periodic table include one of the most common and useful metals and three others that are much less important. Aluminum is the third most abundant element, and it occurs naturally in a wide variety of aluminosilicates, some of which will be described in more detail in Chapter 11. It also occurs in the minerals bauxite, which is largely AIO(OH), and cryolite, Na3AlF6. Although a few relatively rare minerals contain gallium, indium, and thallium, they are usually found in small quantities and are widely distributed. As a result, these elements are generally obtained as by-products in the smelting of other metals, especially zinc and lead. 

J. P. Maher Group III Boron, aluminium, gallium, indium, and thallium, pp. 40-103 (269). 

The known trifluoroacetates of boron, aluminum, indium, and thallium are summarized in Table II. 

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