Aluminium atom

The formation of a fourth covalent bond by the aluminium atom results in spatial rearrangement from the trigonal planar, for three bonding electron pairs, to tetrahedral, for four bonding electron pairs. 

Obviously sufficient energy is available to break the A1—Cl covalent bonds and to remove three electrons from the aluminium atom. Most of this energy comes from the very high hydration enthalpy of the AP (g) ion (p. 78). Indeed it is the very high hydration energy of the highly charged cation which is responsible for the reaction of other essentially covalent chlorides with water (for example. SnCl ). 

Pure anhydrous aluminium chloride is a white solid at room temperature. It is composed of double molecules in which a chlorine atom attached to one aluminium atom donates a pair of electrons to the neighbouring aluminium atom thus giving each aluminium the electronic configuration of a noble gas. By doing so each aluminium takes up an approximately tetrahedral arrangement (p. 41). It is not surprising that electron pair donors are able to split the dimer to form adducts, and ether, for example, forms the adduct. 

The following mechanism of the reaction has been suggested it includes the coordination of the carbonyl compound with the aluminium atom in aluminium sopropoxide and the transfer of a hydride Ion ... 

Since the first structure determination by Wadsley [56] in 1952 there has been confusion about the correct cell dimensions and symmetry of natural as well of synthetic lithiophorite. Wadsley determined a monoclinic cell (for details see Table 3) with a disordered distribution of the lithium and aluminium atoms at their respective sites. Giovanoli et al. [75] found, in a sample of synthetic lithiophorite, that the unique monoclinic b-axis of Wadsley s cell setting has to tripled for correct indexing of the electron diffraction patterns. Additionally, they concluded that the lithium and aluminum atoms occupy different sites and show an ordered arrangement within the layers. Thus, the resulting formula given by Giovanelli et al. 

Almond shell Aluminium, atomized Aluminium, flake Aluminium-cobalt alloy Aluminium-copper alloy Aluminium-iron alloy Aluminium-lithium alloy Aluminium—magnesium alloy Aluminium-nickel alloy Aluminium-silicon alloy Aluminium acetate... 

Solid-state NMR spectroscopy was used for studying the formation of cubic mesoporous aluminophosphate thin films and powders. The analysis of the initial gel, the as-deposited materials and the thermally-treated materials elucidated the changes in the coordination of phosphorus and aluminium atoms and thus revealed how the framework formation and condensation proceeds. The consolidation process in thin films was different than the process in powders. Most probably this could be attributed to the effect of glass substrate. 

The results suggest only that aluminium atoms tend to avoid each other, and are not inconsistent with a proposal that avoidance across four membered rings is most important or a counterproposal that avoidance across six membered rings is more important. If for example at Si/Al = 3.0, diagonal aluminiums across four membered rings are avoided, the structure... 

In other words, only those aluminium atoms which are present in the initiator solution as cations at the moment when it enters the monomer solution are effective in starting polymer chains, the rest of the aluminium chloride becomes inactivated by complexing with the monomer ... 

Figure 4.15 Light-off curve for the dehydration of 2-propanol by a Si8O20-building block catalyst initially containing 3-connected, atomically dispersed aluminium atoms. Conditions 55 mg catalyst, 95ccmin total flow across catalyst, WHSV 0.4 h. ...

It has been reported that aluminium can be introduced into the framework of silicalite with MFI structure by the treatment with AICI3 vapor at elevated temperatures [4-8]. By such treatment, not only Bronsted acid sites but Lewis acid sites are also generated, because aluminium atoms are introduced not only into the framework sites but alkso into the non-framework sites [6-8]. It is expected that this method can be applied to prepare some metallosilicates with MFI structure. Namely, by treating silicalite with metal chloride vapor at... 

First, we should clarify whether metal elements can be introduced into the zeolite framework, and where these elements occupy the framework in the atomplanting method. It is observed by solid state MAS NMR that the signal attributed to tetragonal Al increased greatly after treating silicalite with aluminium trichloride vapor at elevated temperatures. From these results it is concluded that aluminium atoms can be introduced into the zeolite framework by the atom-planting method [7]. 

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