Gallium lower oxidation states

The chemistry of indium complexes of aU types in metal oxidation states lower than +3 has been comprehensively reviewed. Few lower oxidation state mononuclear amido complexes of indium are well characterized, however, and no structure has been reported for an In(I) amide. The compound In N(SiMe3)2 n. which is unstable, " has been characterized NMR spectroscopy but its structure is unknown. The structures of several In(I) complexes, related to amides but outside our current scope, have been described. Like its aluminium and gallium counterparts, the p-diketuninate derivative [ In N(Dipp)C(Me) 2CH] has been characterized, as has the closely related species [ In N(Dipp)C(CF3) 2CH]. ° These feature V-shaped, two-coordination at the metal. The less bulky [(In N(Mes)C(Me) 2-CH)2] ° and 15-2.6-.Vlc,)( (Me) i are dimeric with long In In bonds of... 

Increasing prominence of the lower oxidation state. When a group exhibits more than one oxidation state, the lower state becomes more prominent going down the group. In Group 3A(13), for instance, all members exhibit the +3 state, but the +1 state first appears with some compounds of gallium and becomes the only important state of thallium. 

Hi) Gallium, indium, and thallium. Most of the organic chemistry of gallium, indium, and thallium that merits inclusion in this book is included in the section below on co-ordination compounds. Here are mentioned only lower oxidation states and the instability of hydrides. 

Lower oxidation states become relatively more stable with increasing atomic weight in the IIIB group. Gallium(II) and thallium(II) compounds have been obtained by reactions such as. 

If the pH value in the PAR reagent is lowered to 8.8 by adding a phosphate buffer, gallium(III), vanadium(IV)/(V), and mercury (II) can be detected and may be separated from the other heavy metals with PDCA as the eluent [151]. Fig. 3-157 shows the separation of vanadium(V) that was applied as ammonium(meta)vanadate, NH4V03. Under these conditions, vanadium(IV) elutes after about 17 minutes the two most important oxidation states of vanadium being easily distinguished. Gallium(III), of particular importance for the semiconductor industry, elutes near the void volume. 

Metastable solutions of the monohalides AIX and GaX (X = Cl, Br, I) have been prepared using this technique, and oligomeric species (MX) -L containing a variety of donors (L) have been crystallised. The solutions disproportionate to the trihalide and the metal (equation 2) when warmed to temperatures in the range —40 to - -50°C, depending on the halide, the donor, and the concentration. Species with oxidation states both higher and lower than - -1 (i.e. on the path to both disproportionation products) have been isolated. The reduced species (0 < No. < 1) are discussed in the section on metalloid clusters, and the monohalides and more oxidized species (1 < No. < 3) are discussed here. A sonochemical synthesis of a subvalent gallium species, possibly Gal, has also been developed. 

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