Tetramethylpiperidin-alane adducts tmpH center dot AlX3 (X = Cl, Br, I) and tmpH center dot AlH2Cl: Synthesis, solution behavior, and X-ray crystal structures

2,2,6,6-Tetramethylpiperidine (tmpH) reacts smoothly with aluminum trihalid es AlX3 (X = Cl, Br, I) and monochloroalane AlH2Cl . 2 thf to give the addi tion compounds tmpH . AlX3 (X = Cl, Br, I) and tmpH AlH2Cl, respectively Th ese adducts of the secondary amine tmpH are stable and do not undergo intra molecular elimination of HX or H-2 with formation of the aminoalanes tmpAlX (2) or tmpAl(H)Cl. In the solid state, tmpH . AlX3 (X = Cl, Br, I) and tmpH . AlH2Cl are tetracoordinated molecular adducts. While this is also true f or solutions of tmpH . AlX3 (X = Br, I) and tmpH . AlH2Cl, the compound tmp H . AlCl3 dissolves in CH2Cl2 as the salt [tmpAlCl(3)]-tmpH(2) and the addu ct tmpH . Al2Cl6, as is evident from its NMR spectra and from conductivity measurements. This behavior is supported by a semiempirical AM1 calculation .