Dehydrogenative Dual Ammonia Activation and Transfer by an N-Heterocyclic Boryloxy Aluminyl Compound.

The reactivity of an N-heterocyclic boryloxy (NHBO) ligated aluminyl compound has been harnessed for main-group-mediated dehydrogenative dual activation of ammonia. The Al(I) system K[{(HCDippN)₂BO}₂Al] reacts with excess NH₃ to give the Al(III) bis(amide) K[{(HCDippN)₂BO}₂Al(NH₂)₂] and in the process generates H₂. The initial stage of the reaction proceeds via formal N-H oxidative addition at Al(I) (via a coordination/proton shuttling sequence) to give an aluminium(III) primary amido hydride. Subsequent protonolysis of the strongly hydridic Al-H bond selectively yields the corresponding aluminium bis(amide) and H₂. This step occurs without competing protolytic ligand loss - exploiting the limited basicity of the supporting [(boryl)O]^- donors. In terms of amide transfer reactivity, the utility of K[{(HCDippN)₂BO}₂Al(NH₂)₂] in delivering one or both equivalents of [NH₂]^- to electrophilic substrates (HBpin, CO₂ and Ph₂CO) has been demonstrated.