Tetramethylpiperidine-alane adducts tmpH.AlX3 (X = Cl, Br, I) and tmpH.AlH2Cl. Synthesis, solution behavior, and x-ray crystal structures

2,2,6,6-Tetramethylpiperidine (tmpH) reacts smoothly with AlX3 (X = Cl, Br, I) and AlH2Cl.2THF to give the addn. compds. tmpH.AlX3 (X = Cl, Br, I) and tmpH.AlH2Cl, resp. These adducts of the secondary amine tmpH are stable and do not undergo intramol. elimination of HX or H2 with formation of the aminoalanes tmpAlX2 or tmpAl(H)Cl. In the solid state, tmpH.AlX3 (X = Cl, Br, I) and tmpH.AlH2Cl are tetracoordinated mol. adducts. While this is also true for solns. of tmpH.AlX3 (X = Br, I) and tmpH.AlH2Cl, the compd. tmpH.AlCl3 dissolves in CH2Cl2 as the salt [tmpAlCl3]-tmpH2 and the adduct tmpH.Al2Cl6, as is evident from its NMR spectra and from cond. measurements. This behavior is supported by a semiempirical AM1 calcn. [on SciFinder (R)]