Intriguing Reactivity of a 1,2-Dihydrodialumane Towards Organic Azides - From a Terminal Diazido-Dialumane to Pendulum-Clock-Like Azide Bridging.

Abstract

The reactivity of dihydro-dialane with organic azides is described. Treatment of the hybrid ligand-based dialane [(DNI{H}Al)₂] (I) (DNI = [3,3-dimethyl-2-2-methyl-2-(2,6-diisopropylaniline)ethenyl]-3H-indolenine) with TMSN₃ (TMS = trimethylsilyl) at room temperature gives the first diazido-dialane [(DNI{N₃}Al)₂] (1). The transformation from here to a more stable aluminium-tetrazole [DNIAl(NTMS)₂N₂] (2) is established. The reaction of other RN₃ gives [(DNI{H}Al)₂(κ²-N₃R)] (R = Benzyl in 3 and 1-Adamantyl in 4) with the azide in a μ-bridging position between two aluminium atoms. Using ¹H NOESY/EXSY NMR spectroscopy, a positional exchange of the two TMS groups (2) via rotation of the tetrazole unit is observed. In contrast, compound 3 exhibits a pendulum-clock-like dynamic, with N_α oscillating between the two aluminium atoms in solution. The reaction of dialane I with DippN₃ (Dipp = 2,6-ⁱPr₂-C₆H₃) gives the dialuminium amine [{DNI(H)Al}₂(μ-NDipp)] (5).