UC Davis

The reaction of :AlAr^iPr8 (Ar^iPr8 = C₆H-2,6-(C₆H₂-2,4,6-ⁱPr₃)₂-3,5-ⁱPr₂) with Ar^Me6N₃ (Ar^Me6 = C₆H₃-2,6-(C₆H₂-2,4,6-Me₃)₂) in hexanes at ambient temperature gave the aluminum imide Ar^iPr8AlNAr^Me6 (1). Its crystal structure displayed short Al-N distances of 1.625(4) and 1.628(3) Å with linear (C-Al-N-C = 180°) or almost linear (C-Al-N = 172.4(2)°; Al-N-C = 172.5(3)°) geometries. DFT calculations confirm linear geometry with an Al-N distance of 1.635 Å. According to energy decomposition analysis, the Al-N bond has three orbital components totaling -1350 kJ mol^-1 and instantaneous interaction energy of -551 kJ mol^-1 with respect to :AlAr^iPr8 and Ar^Me6N̈:. Dispersion accounts for -89 kJ mol^-1, which is similar in strength to one Al-N π-interaction. The electronic spectrum has an intense transition at 290 nm which tails into the visible region. In the IR spectrum, the Al-N stretching band is calculated to appear at ca. 1100 cm^-1. In contrast, reaction of :AlAr^iPr8 with 1-AdN₃ or Me₃SiN₃ gave transient imides that immediately reacted with a second equivalent of the azide to give Ar^iPr8Al[(NAd)₂N₂] (2) or Ar^iPr8Al(N₃){N(SiMe₃)₂} (3).