Reactivity of a Bulky Bora‐Amidine Ligand with Trimethylaluminum

Reaction of Me3Al with HB[N(H)DIPP]2 (DIPP = 2,6‐iPr2‐C6H3) in hexane gave a complex mixture of compounds instead of HB(N‐DIPP)2AlMe. After addition of THF, one of the products could be trapped in trace amounts and was characterized by crystal structure determination: DIPP–N(H)B(H)(N–DIPP)AlMe2·THF (1). Heating a hexane or fluorobenzene solution of HB[N(H)DIPP]2 and Me3Al in the absence of THF gave a relatively clean conversion and allowed for the isolation of [(DIPPNH)AlMe2(μ‐H)AlMe2]2 (2), a product that was formed through B/Al ligand exchange. Complex 2 contains protic and hydridic hydrogen atoms in close vicinity. The compound remains intact upon heating, however, it readily releases H2 when dissolved in THF forming DIPPN(AlMe2·THF)2 (3). The latter bimetallic complex contains two THF stabilized Lewis acidic central aluminum atoms in close proximity.