Syntheses and Structural Characterization of a LAl(N3)N[μ-Si(N3)(tBu)]2NAl(N3)L and a Monomeric Aluminum Hydride Amide LAlH(NHAr) (L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3)

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Reactions between the aluminum(I) monomer LAl (L = HC[(CMe)(NAr)] 2, Ar = 2,6- i Pr 2 C 6 H 3 ) and organic azides (RN 3, R = C 10 H 15 (adamantyl), Ph 3 Si; t BuSi(N 3 ) 3 ) are reported. LAl reacted with the bulky azide RN 3 in toluene in a temperature range of −50 to 25 °C, resulting in the compound LAl[(NR) 2 N 2 ] (R = C 10 H 15 ( 1 ), Ph 3 Si ( 2 )) instead of the expected Al N multiple bond species, while the reaction with t BuSi(N 3 ) 3 gave LAl(N 3 )N[(μ-Si(N 3 )( t Bu)] 2 NAl(N 3 )L ( 3 ). Compounds 1 − 3 have been fully characterized by mass spectrometry and IR and multinuclear NMR spectroscopy ( 1 H, 13 C, and 29 Si) as well as by single-crystal X-ray crystallography. The structural analysis of 1 and 2 reveals an AlN 4 planar five-membered ring compound, suggesting a [2 + 3] cycloaddition of the Al N multiple bond species with a molecule of RN 3 despite the steric bulk of the L and R substituents. Compound 3 shows a bonding of the N 3 group to the Al and a formation of the N 2 Si 2 central core, implying the migration of N 3 and a [2 + 2] cycloaddition in the reaction sequence. In addition, the solvent-free reaction of an aluminum dihydride LAlH 2 with ArNH 2 was also investigated at elevated temperatures (150−290 °C), and a monomeric aluminum hydride amide, LAlH(NHAr) ( 4 ), was obtained as the only isolable product. The Al−H and N−H groups of 4 are shown in the IR and 1 H NMR spectra. The corresponding X-ray structural analysis exhibits the Al−H and N−H bonds that are nearly arranged in position trans to the Al−N NHAr bond.