The Group 13 Elements Al, Ga, In

The electronic structures and some other fundamental properties of the Group 13 elements are listed in Table 6-1. 

Whereas for the smallest member of Group 13, boron, cationic species of the type [B(H20)6]3+ are unknown, the remaining four elements have a rich cationic chemistry, in line with their metallic character. They also form many molecular compounds that are covalent. 

Electronic configuration Ionization enthalpies (kJ mor1) [Ne]3s23p [Ar]3d104s24p [Kr]4 f 5s25p [Xe]4/145d 6s 26p 

The stereochemistries and oxidation states of Group 13 are summarized in Table 6-2. 

Aluminum, the commonest metallic element in the Earth s crust (8.8 mass %) occurs widely in Nature in silicates such as micas and feldspars, as the hydroxo oxide (bauxite), and as cryolite (Na3AlF6). In spite of the abundance, aluminum does not appear to play a role in biology, although it has been linked to Alzheimer s disease, a degenerative brain disorder. 

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Poly(pyrazolyl)borato alkyl derivatives of the Group 13 elements (Al, Ga, In, Tl) have been synthesized for all members with the exception of thallium. 

In covalent azides, the pseudohalogen azide RN3 has an angular structure as in HN3. Triazidoborazine [H3N3B3(N3)3] and other boron azides, for example, salts of the tetraazidoborate ion B(N3 (4 have been considered as boron nitride precursors (see Boron-Nitrogen Compounds). The M(Ns)3 azido complexes of the other group 13 elements (Al, Ga, In, Tl) and their M(N3)4 tetraazido anions are all known. They and their derivatives are also used as precursors for the nitrides. 

Organoantimony compounds with bonds between Sb and group 13 elements were discussed in a recent review. They are known as Lewis acid-base adducts R3Sb-MR3 (M = Al, Ga, In) and as four- or six-membered heterocycles (R2Sb-MR2) (n = 2, 4). Pyrolysis of these compounds leads to the semiconducting materials AlSb, GaSb, and InSb. 

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