Gallium, Indium, and Thallium Compounds

Table VIII also includes a series of gallium, indium, and thallium compounds of the general formula Cp(CO)3M 3E (E,M = Ga,W In,Cr In,Mo ...

By itself not particularly strong or durable, aluminum in combination with other metals becomes one of the most versatile materials available. It does take vast amounts of electrical energy to manufacture, however, and presently this involves the production of both carbon dioxide and the sulfur oxides. Alums are astringents and the sources of beautiful crystals. Alumina, the oxide, comes in a variety of polymorphs used as various abrasives and in beautiful, gem-quality minerals. It is also the product of the extremely exothermic thermite reaction. Boron Neutron Capture Therapy (BNCT) offers a potential treatment against brain tumors and other difficult-to-treat carcinomas of the head and neck. Gallium, indium, and thallium compounds do not have many applications. 

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. 

Consequently, due to preferred cis-cis orientation a dimeric structure is observed for the indium complex and an unprecedented cis-trans arrangement in the thallium structure leads to a polymeric aggregate. Further N-NMR spectroscopic studies show that the aluminum and gallium complexes are stable contact ion pairs even in solution whereas the indium and thallium compounds are solvent-separated ion pairs in THE solution. 

KT1 does not have the NaTl structure because the K+ ions are too large to fit into the interstices of the diamond-like Tl- framework. It is a cluster compound K6T16 with distorted octahedral Tig- ions. A Tig- ion could be formulated as an electron precise octahedral cluster, with 24 skeleton electrons and four 2c2e bonds per octahedron vertex. The thallium atoms then would have no lone electron pairs, the outside of the octahedron would have nearly no valence electron density, and there would be no reason for the distortion of the octahedron. Taken as a closo cluster with one lone electron pair per T1 atom, it should have two more electrons. If we assume bonding as in the B6Hg- ion (Fig. 13.11), but occupy the t2g orbitals with only four instead of six electrons, we can understand the observed compression of the octahedra as a Jahn-Teller distortion. Clusters of this kind, that have less electrons than expected according to the Wade rules, are known with gallium, indium and thallium. They are called hypoelectronic clusters their skeleton electron numbers often are 2n or 2n — 4. 

Compounds with Bonds between Transition Metals and Three-Coordinate Gallium, Indium, and Thallium... 

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. 

B. Compounds of Aluminum, Gallium, Indium, and Thallium 1. Simple Organometa Amides... 

Aluminum, gallium, indium, and thallium have been successfully incorporated in cyclic systems, although little structural information has been obtained (75). Hoberg (34) has prepared many such ring compounds, including, for example, 8a and 8b, and has demonstrated the former to be dimers from molecular mass determinations and from mass spectra. 

A. McKillop, J. D. Smith, and 1. J. Worrall, Organometallic Compounds of Aluminium, Gallium, Indium and Thallium. Chapman Hall, London, 1985. 

Compounds containing E-E single bonds between the heavier elements of Group 13 received considerable interest in the last decades and developed to a broad field in current organoelement chemistry with a multitude of different formulas and types of structures. The first synthesis of a tetraalkyldielement(4) derivative in 1988 marked the starting point for many aspects of that chemistry and influenced the further development of organoelement chemistry with aluminum, gallium, indium, and thallium in unusual oxidation states to a considerable extent. Some of the first cluster... 

The elements of group Illb, gallium, indium, and thallium, are very rare and have small practical importance. Their principal compounds represent oxidation state - -8 thallium also forms thailous compounds, in which it has oxidation number - -1. Gallium is liquid from 29° C. its melting point, to 1700 C, its boiling point. It has found use as the liquid in quartz-tube thermometers, which can be used to above 1200° C. 

Methyl, ethyl, propyl, and butyl halides are reduced at lead and tin cathodes to produce, respectively, the corresponding tetraalkyllead and tetraalkyltin compounds in excellent yield. Bismuth, gallium, indium, and thallium can be employed to prepare a variety of organometallic compounds. Feoktistov [2] and Hawley [4] have summarized many of these electrosyntheses. 

Application of this procedure to the post-transition metals forming clusters indicates that bare gallium, indium, and thallium vertices contribute one skeletal electron bare germanium, tin, and lead vertices contribute two skeletal electrons bare arsenic, antimony, and bismuth vertices contribute three skeletal electrons and bare selenium and tellurium vertices contribute four skeletal electrons in 2D and 3D aromatic clusters. Thus, Ge,Sn, and Pb vertices are isoelectronic withBH, Fe(CO)-, andC5H5Co vertices and As, Sb, and Bi vertices are isoelectronic with CH, Co(CO)v and C H Ni vertices in bare metal cluster compounds. 

The compounds R3MC and RM3C3 are the only known compositions that exist in the rare-earth-metal-(aluminium, gallium, indium and thallium)-carbon systems at the present time. A number of reports on the preparation of cubic perovskite-type carbides containing rare earth elements with the general formula RjMC 00 (Jeitschko et al. 1964, Rosen and Sprang 1965, Haschke et al. 1966a, b, Nowotny 1968) contain little information about their properties other than their lattice parameters. 

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