Isolation of new polynuclear aluminium amides; trinuclear [AlCl(MeNCH2CH2NMe)2(Al(NMe2)Cl)(Al(NMe2)2)] and fluxional adamantane-like [Al4Cl2(NMe2)6(NMe)O]

In attempted transamination reactions involving [Al2(NMe2)6] and the amines, N,N′-dimethylethylenediamine, DMEDA, or diethylenetriamine, DETA, insoluble white powders were formed. Two unexpected compounds, trinuclear [AlCl(MeNCH2CH2NMe)2(Al(NMe2)Cl)(Al(NMe2)2)] (1) and adamantane-like [Al4Cl2(NMe2)6(NMe)O] (2) were isolated in similar reactions where the aluminium amide sample [Al2(NMe2)6] contained some 1% residual chloride. Compound 2 was also identified (by NMR and mass spectroscopy) as the major product from the reaction between Al2Cl6 and LiNMe2 (1:5) in the presence of traces of water. The compounds 1 and 2 have been characterized by X-ray crystallography, mass spectroscopy and NMR. Variable temperature solution phase proton NMR shows that there is inversion at nitrogen in the bridging amides in adamantanoid structure 2.