IIIB Metals

Group-IIIB elements (i.e. B, Al, Ga, In and Tl) have an odd number of valence electrons in the fairly weakly bound s and p atomic shells. Unlike the group-II case, one could expect these elements to behave like simple metals, with properties determined by the average valence-electron density. Instead, the evolution of physical and chemical properties within the group is far from simple and monotonic. 

First of all, as is often the case, the lightest element in the group (i.e. B) behaves quite differently from all the others, as it is a semiconductor with a fairly large band gap (1.5 eV, from Ref. [50]). For B, three complex crystal structures are known, all based on the packing of hollow B12 icosahedra [159]. 

As any solid-state textbook reports, bulk aluminum is a nearly free-electron fee metal, characterized by a very high valence-electron density. Gallium, on the other hand, is liquid at temperatures close to room temperature, and displays two complex crystal phases at lower temperatures. Finally, indium and thallium recover most of the simple metal properties displayed by aluminum, with, however, a few peculiar properties that indicate an increased tendency towards covalent bonding in their chemistry. 

This alternation of properties suggests that clusters of group-IIIB elements could display an intriguing variety of structures and properties. Unfortunately, extensive experimental data is available only for clusters of the simplest of these elements, i.e. aluminum. Less systematic but nevertheless abundant data has also been reported for indium. Boron, gallium and thallium clusters, by contrast, have been only marginally investigated in experiments. 

Aluminum clusters have been investigated using a variety of experimental techniques, providing abundance spectra [164, 165], spin multiplicities [166], IPs [164, 167], EAs, and static polarizability [105]. Reactivity studies have been reported for size-selected A1 clusters in contact with a variety of small molecules (see, for instance, [167]), and the presence of different isomers in a population of clusters has been investigated by measuring the mobility of clusters in a buffer gas [168]. Finally, the electronic structure of these clusters has been probed by photoelectron spectroscopy on the anion species Al [169, 170]. As mentioned above, bulk aluminum is remarkably close to a nearly 

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Anionic metal bases react with group-IIIB halides by eliminating halide anions, forming neutral, c-bonded IIIB-metal compounds ( 6.5.2.2) ... 

Organic Derivatives of Group IIB and Group IIIB Metals... 

In this section, we will discuss organometallic derivatives of zinc, cadmium, mercury, and indium. The group IIB and IIIB metals have the d10 electronic configuration in the 2+ and 3+ oxidation states, respectively. Because of the filled d level, the 2+ or 3+ oxidation states are quite stable, and reactions of the organometallics usually do not involve changes in oxidation level. This property makes the reactivity patterns of these organometallics more similar to those of derivatives of the group IA and IIA metals than to those of derivatives of transition metals with vacancies in the d levels. The IIB metals, however, are... 

SECTION 7.3. ORGANIC DERIVATIVES OF GROUP IIB AND GROUP IIIB METALS... 

Again the reactivity is determined by steric factors. For example, La(btsa)3 does not show any tendency to react with group(IIIB) metal alkyls under these conditions [89]. However, total ligand exchange has been proven in Sm(btsa)2(THF)2 and KSm(btsa)3 by NMR- and IR-spectroscopy to yield the first Sm(II) alkyls [89]. 

The alkali metals, the alkaline earth metals, the group IIIB metals, aluminum, zinc, cadmium, and silver have ions with charges equal to their classical group numbers, but only in their compounds When the elements are uncombined, they do not form ions, and the charge on each atom is zero. 

The Group lA, IIA, and IIIB metals, zinc, cadmium, silver, and aluminum form a single type of ion with charge equal to the metal s classical periodic group number. 

Reactions at a Group IIIB Metal Center 10.2.4.5. Metal Carbonyls and Other Transition Metal Compounds... 

Reactions of transition metal carbonyls with an In(I) center also take place by oxidative addition here InX inserts into the M-X bond. Oxidative addition to the low-valent halides of Ga, In, or T1 thus provides a useful route to compounds with group IIIB-metal bonds This approach is particularly useful when the salt elimination route cannot be employed because a suitable transition metal nucleophile is lacking. 

Under conditions used for hydroboration the other group IIIB metal hydrides do not react with olefins. AIH3 requires temperatures near 80°C to react with terminal olefins to generate the aluminium alkyls, though this process is again reversible. The commercial production of (C2H5)3A1 ... 

Inring, H.M. and Rossotti, F.J.C. (1952). The solvent extraction of group IIIB metal halides. Analyst, 77. 801-812. 

The rare earth elements here referred to include the group IIIB metals (Sc, Y and La) and the lanthanide elements (Ce to Lu) and are sometimes loosely referred to as lanthanide elements, as the main characteristics and reactivity of these elements are similar in many cases. 

H. Irving and P. J..C. Hoasottlj "Solvent Extraction of Group IIIB Metal Halldea", Analyst 2Z>, B01 (1952). 

R ligands which may effectively prevent solvent molecules from entering the yttrium coordination sphere. It is relevant to mention here the compounds CpJTiR (R = H, CH ) which don t show benzene metallation not even when solutions of CpJTiR are heated for prolonged periods in at 90 C (vide supra). This clearly demonstrates the difference between Ti on one side and Group IIIB metals and lanthanides on the other. 

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