N-Tosyl Hydrazone Precursor for Diazo Compounds as Intermediates in the Synthesis of Aluminum Complexes

The one-pot reaction of LAlH₂ (1; L = HC(CMeNAr)₂, Ar = 2,6-iPr₂C₆H₃) with N-tosyl hydrazone as a precursor for preparing the diazo intermediate resulted in an aluminum compound with the composition LAl[OS(O)Ar]NHN=CMePh, (Ar = 4-Me-phenyl (2); LAl(H)NHN=CHR, R = 2-thienyl (3), 2-F-phenyl (4)). This is the first example of utilizing N-tosyl hydrazone as precursor of diazo ligands for aluminum compounds. Compound 2 with Al-O-S(O)-C and the Al-N(H)N=C chains was obviously obtained via the reaction of LAlH₂ (1) with the intermediates given in Scheme 2. In contrast, compounds 3 and 4 exhibit only one Al-N(H)N=C chain due to the different behavior of the substituents R. It is worth mentioning that complex 5 with five-coordinate aluminum was obtained directly from the reaction of N-tosyl hydrazone with LAlH₂. In compound 5, the aluminum atom functions as the center of three heterocycles. LAl(H)NHAr (Ar = 2,6-iPr₂C₆H₃) (6) was obtained via the decomposition of the educts at 110 °C. Complexes 2-6 were characterized by NMR and single-crystal X-ray diffraction studies. Additionally, the hydroboration of benzaldehyde catalyzed by 1-6, respectively, was studied, affording the corresponding product in high yield.