Aluminum subhalide

Facile routes for the convenient syntheses of similar complexes of the aluminum(II) subhalides do not exist at all. These compounds [X2(L)A1-A1(L)X2 (X = Cl, Br, I L = NMe2SiMe3, OEt2, PEt3, MeOPh)] were obtained in low yields by the treatment of metastable solutions of aluminum monohalides A1X with the corresponding donor substances similar to the reactions described in Eq. (3).33 35 A12C14 was supposed to be formed from elemental A1 and A1C13 at 120 °C in a solvent, however, it was not isolated in a pure form and was characterized on the basis of some not really specific reactions.36 In view of the results obtained recently with respect to the synthesis and stability of aluminum subhalides,33 35 it seems to be rather implausible that indeed considerable concentrations of a subhalide had formed. Quantum-chemical calculations... 

In this procedure, extensively tested by Alcan at one time, dissolution of aluminum from the alloy using aluminum trichloride at about 1,300°C produces the volatile aluminum subhalide [19]. Cooling the subhalide moderately returns a pool of molten product aluminum, and aluminum trichloride (boiling point approximately 183°C), which serves as a working fluid and can be recycled. Despite problems with the aluminum recovery methods there remains an interest in nonelectrolytic aluminum production, such as that offered by carbothermic processes [20]. 

In contrast to the non-trivial routes for the syntheses of pure aluminum(I) or gallium(I) subhalides, indium(I) chloride or bromide can simply be prepared by melting mixtures of elemental indium and indium trihalides [39]. When these in-dium(I) halides were treated with bulky alkyllithium compounds, deep violet orga-noelement indium dusters (13-18) were obtained [Eq. (3)] [40, 41]. 

Three cluster compounds are worth mentioning in context with the particular topic described here. The subhalides A122C120(L)12 (L = THF, THP) and Al22Br20(L)12 (L = THF) possess cluster cores formed by icosahedra of twelve A1 atoms.41,42 Ten of these cluster atoms are terminally attached to A1X2(L) substituents (X = Cl, Br) via Al-Al single bonds. The Al-Al bond lengths are 254.9, 255.2, and 252.6 pm, respectively, and correspond well to those detected for the aluminum(II) subhalides 1 to 5 (Table I). 

Ping-Yan Wang et al., Study on Produetion of Aluminum Carbothermie Reduetion and Subhalide Decomposition under Vaeuum , Non-ferrous metal(Smelting part),2 ( 2005 ), 11—13. 11. Qiu-Xia Li et al., Preparation of Alurrunum by Disproportion of Sub-fluoride in Vaeuum ,... 

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