Synthesis of amino- and amido-aluminium derivatives and investigation of their dynamics in solution

The salts Li[Al(C4H8N)4]·nC4H8NH (n= 1, 2; C4H8NH = pyrrolidine) have been prepared and characterised in solution by 1H-, 13C-, 7Li- and 27Al-NMR spectroscopy. Their reaction with AlCl3(Cl/Li molar ratio = 3) affords the binary amido derivative [Al(C4H8N)3]2, which, on turn, is reactive towards AlX3, yielding [AlX2(C4H8N)]2(X = Cl, CH3). The binuclear derivatives [AlY2(C4H8N)]2(Y = Cl, CH3, C4H8N) react with [NH2Et2]Cl affording the amine complexes AlY2Cl(C4H8NH)n(Y = CH3, n= 1; Y = Cl, n= 1, 2). Alternatively, the monochloro species Al (CH3)2Cl(C4H8NH) results from the reaction of Al(CH3)3(C4H8NH) and AlCl3(C4H8NH)(CH3/Cl molar ratio = 2). The dichloro-methyl derivative Al(CH3)Cl2(C4H8NH) is obtained by reacting Al(CH3)3(C4H8NH) and AlCl3 (C4H8NH)(Cl/CH3 molar ratio = 2). The Lewis adducts AlCl3(amine)n(amine = pyrrolidine, n= 1, 2; amine =N,N,Ntrimethylpropanediamine, n= 1) have been isolated when AlCl3 was contacted with the stoichiometric amount of the amine. At variance with N,N,N-trimethylpropanediamine, N,N,N-trimethylethylenediamine and N,N,N,Ntetramethylethylenediamine react with AlCl3 yielding the salt derivatives [AlCl2(amine)2][AlCl4].The dynamic processes of the coordinated amine ligands of AlCl3(amine)n(amine = pyrrolidine, n= 1, 2; amine =N,N,Ntrimethylpropanediamine, n= 1) and [AlCl2(amine)2][AlCl4](amine =N,N,N,N-tetramethylethylenediamine) have been investigated in solution by NMR spectroscopy.