Reducing hybrid ligand-based alane and chasing aluminium(i): dialane and unusual transient dialumene

Abstract

In this work, an alane, [DNIAlH₂] (1) (DNI = 3,3-dimethyl-2-[2-methyl-2-(2,6-diisopropyl-aniline)ethenyl]-3H-indolenine), stabilised by a hybrid ligand was reduced by Jones's Mg(I) ([(^MesBDIMg)₂]) and Roesky's Al(I) ([^DippBDIAl:]). The resulting dialane compound [{DNI(H)Al}₂] (2) was characterised using NMR spectroscopy, mass spectrometry, DFT calculations and single-crystal XRD experiments. The reaction of aluminium dihydride [DNIAlH₂] (1) with [^DippBDIAl:] at high temperatures gives an intramolecular C(sp²)–H bond-activated compound 3. To study the monomeric hybrid ligand-based Al(I), characterisations and computational calculations were performed, which elucidate that compound 5, consisting of two inequivalent aluminium atoms in an Al₂CN four-membered ring, resulting from the activation of a carbon–nitrogen bond in the reaction of [DNINa] with [(Cp*Al)₄].