Group 13 Metals - Gallium, Indium, Thallium

Secondary mercury-nitrogen bonds leading to supramolecular self-assembly have been found in methylmercury-2-5 -methylthiouracylate (Hg- N 3.03 A) [134] and in -adeninato-//-iV, Ar -bis(methylmercury) (Hg-N 2.057-2.063 A, Hg- -N 2.80-2.87 A) [135]. 

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Reference has been made earlier to scattered rare metals, the five most important members of this particular group being gallium, indium, thallium, rhenium, and germanium. A common feature of these metals is that they do not form commercially significant mineral sources of their own, but are invariably produced from the processing of other mineral sources. The description given here pertains to rhenium, and serves as one example of these dispersed metals. 

Keywords Group 13 metals (aluminum, gallium, indium, thallium), Ambidentate ligands, Phosphorus-nitrogen bidentate ligands, Pyridyl phosphanes, Aminoiminophosphoranes, Lewis acid catalysis... 

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. 

The poor metals among the BCNOs usually include aluminum, gallium, indium, thallium, tin, lead, and bismuth. The metalloids are boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. The nonmetals are carbon, nitrogen, oxygen, phosphorus, sulfur and selenium. These groups are not official, and chemists sometimes disagree on whether a particular element like boron should be called a metal or a metalloid. 

Group 13 Metals - Aluminum, Gallium, Indium, Thallium... 

For a discussion of the atomic properties of the group 13 metals see Downs AJ (1993) In Downs AJ (eds) Chemistry of aluminum gallium, indium and thallium. Blackie, London, Chapter 1... 

The discussion of the main group 3-5 and 3-6 compounds in the previous sections was limited to examples in which the group 3 element E is three-coordinate, so that an empty p-orbital on E is available for overlap with a lone pair on the group 5 or 6 atom. For the same reason, the discussion here will focus on those compounds with three-coordination at gallium, indium, or thallium. In the case of the transition metal derivatives, it is transition metal -electrons that are available to overlap with the empty p-orbital on E to form the potential ir-bond, as illustrated in Fig. 26. 

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