Bis(tetramethylpiperidino)aluminun halides tmp2AlX (X = Cl, Br, I) are sufficiently Lewis-acidic to form 1: 1 adducts tmp2AlX.sum.Do (Do = thf, py, lutidine, isoquinoline). While cation formation [tmp2AlDo]+ could not be achieved by replacing X- in tmp2AlX.sum.Do with BPh4-, B(C6F5)4- or tosylate, the formation of [tmp2AlDo]+ is possible by using tmp2Al(I)py and AlI3. AM1 calcns. show that [tmp2Al.sum.py] AlI4 is a ionic compd. while tmp2 AlCl.sum.py reacts with AlCl3 to the \"bridged\" complex tmp2 Al(py)Cl.sum.AlCl3. Reactions with the anion B11CH11Cl-.sum.aimed at the formation of tmp2Al+ will also be reported. [on SciFinder (R)]