Gallium species

In addition, it should be possible to extend the range of compounds to include aluminum and indium. In principle, there are no compelling reasons why these analogues of the currently known gallium species should not exist. The aluminum compounds would be of particular interest as calculations on the neutral frans-bent HAlAlH model species indicate a bond strength of 10 kcal moP which is over three times higher than that calculated... 

While no aluminum derivatives featuring the 1,8-naphthalenediyl backbone have ever been isolated, several gallium species have been successfully prepared. With the... 

The finding of the low-temperature activation of propane on zeolite Ga/HZSM-5 indicates a bifunctional reaction mechanism 179,181. The highly dispersed gallium oxide species in close vicinity to the Bronsted acid sites promote the initial activation of propane. Derouane et al. 179,181 further showed that hydrogen inhibits the activation of propane. This effect was explained by a competitive adsorption of hydrogen on the gallium species or even by a reduction of Ga to Ga species. 

In ALE, growth proceeds by the deposition of a monolayer per cycle. As an example, in the ALE growth of GaAs, the surface is exposed to trimethylgallium until the surface is saturated with a monolayer of gallium species (the actual species is unknown). The gallium precursor is flushed out and arsine is introduced, which results in the formation of a layer of... 

The aluminium compound, (Et2AlAsBu2)2, obtained from triethylaluminium and dibutylarsine by loss of ethane contains a four-membered ring (As—A12.57 A) and, as shown in Table 3, four-membered, often planar and centrosymmetric rings dominate the related arsenic-gallium species 62. The geometry at each of the ring atoms is distorted tetrahedral. 

The greater acid strength of Bronsted- and Lewis-acid sites associated with framework and extra-framework gallium species, respectively, is also reflected by the greater heats of ammonia adsorption. These effects are not surprising since, as generally known from chemistry textbooks, gallium oxide is more acidic than aluminum oxide. 

We will present the use of the tris(trimethylsilyl)silyl group (hypersilyl) [14] to stabilize low valent gallium species. 

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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