Organoaluminiums

Many organoaluminium compounds are known which contain 1, 2, 3 or 4 Al-C bonds per A1 atom and, as these have an extensive reaction chemistry of considerable industrial importance, they will be considered before the organometallic compounds of Ga, In and T1 are discussed. 

It is interesting to note that the reaction of Etl with Al metal to give the sesqui-iodide Et3Al2l3 wa.s the first recorded preparation of an organoaluminium compound (W. Hallwachs and A. Schafarik, 1859). 

Heterocyclic and cluster organoaluminium compounds containing various sequences of Al-.N bonds are discussed on p. 265. 

As in the case of organoaluminium compounds, unusual stereochemistries can be imposed by suitable design of ligands. Thus, reaction of GaCh with 3,3, 3"-nitrilotris(propylmagnesium... 

When exposed to air the organoaluminium shell is transferred to an AI2O3 matrix where the Pt clusters are regularly dispersed (Figure 15). This is a promising pathway for preparing solid catalysts (cf. Section 4.1). 

Controlled decomposition of organometallics leads to nanocatalysts which exhibit a very clean and truly zerovalent metallic surface (cf. [339]). As indicated in Figure 15 in Section 3.10, the organoaluminium shell of the one-shell Pti3 cluster (size 0.75+0.1 nm) obtained via the decomposition of [(COD)Pt(CH3)2] in the presence of excess trioctylaluminium [352] is transferred to an AI2O3... 

Organoaluminium derivatives with the formuia RxAIZ3 x (Z = OR, OH, X) give rise to explosive reactions with methanol and ethanol. With very strong bases, the reaction can be written down as ... 

Hoffmann, E. G. Adiabatische Kryometrie und ihre Anwendung auf Organoaluminium-Verbindungen. Liebigs Ann. Chem. 629, 104 (1960). 

The first organoaluminium complex that catalysed a Diels Alder reaction was formed from menthol and ethylaluminium dichloride. This finding was complemented by work of Corey who showed that the aluminium diamine complex (49) was effective for controlling the stereochemistry of Diels-Alder reactions involving cyclopentadiene and acryloyl and crotonyl amides (e.g. 

In addition, Wipf and co-workers104 have used silver(i)-catalyzed addition of zirconocenes to 3,4,6-tri-O-benzyl-D-glucal epoxide 93 for the stereoselective synthesis of a-C-glucosyl compounds 95 and 96 following a similar mechanism as in the reaction with organoaluminium and organoboron reagents (Scheme 32). 

The catalyst component consists of halides of IV-VIII group elements having transition valence and the cocatalysts are organometallic compounds like alkyls, aryls and hydrides of group I-IV metals. Although there are hundreds of such catalyst cocatalyst systems listed in table below. Systems based on the organoaluminium compounds such as triethyl aluminium (AlEt3) or diethyl aluminium chloride... 

Holloway, C. E. Melnik, M. Organoaluminium compounds classification and analysis of crystallographic and structural data. J. Organomet. Chem. 1997, 543, 1-37. 

Other hard carbon nucleophiles, such as organoaluminium [31] or organoboron [32, 33] reagents, are also applicable to the Pd-catalyzed SN2 substitution of pro-... 

The narrow molecular weight distributions accomplished by the supported catalysts were attributed to the absence of any organoaluminium co-catalyst dissocia-tion/reassociation processes at the heterogenized active neodymium centers. Furthermore, the order of the grafting sequence seemed to have minor implications for the catalyst performance. Control experiments have been conducted to explain the lower activity [0.9 (47) and 1.1 kg-PBD molNd h (48)] of the supported neodymium catalyst. Accordingly, an increase of the catalyst concentration (48) and use of a nonporous silica support (49) suggested that monomer diffusion and accessibility of the Nd centers are limited by the relatively small mesopores [dp = 2.4 (47) and 2.5 nm (48), after grafting]. 

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