Monomeric, N-functionalised amido complexes of aluminium: Synthesis of [AlCl{NR(8-C₉H₆N)}₂] (R = H or SiMe₃) and [Al{N(2-C₅H₄N)-(2-C₅H₄N)} ₃]

Routes have been devised to a series of aluminium(III) amide complexes containing either of the bulky, N-functionalised amides NR(8-C₉H₆N)^- (R = H or SiMe₃) or N(2-C₅H₄N)₂^-. Reaction of the lithium amides [{Li(OEt₂)[NR(8-C₉H₆N)]}₂] (R = H or SiMe₃) with AlCl₃ afforded [AlCl(NR(8-C₉H₆N)]₂] (R = H or SiMe₃) respectively. The crystal structure of five-co-ordinate [AlCl(NH(8-C₉H₆N)}₂] shows it to be monomeric in the solid state with intramolecular dative interactions between the aluminium centre and both aromatic nitrogen atoms. Treatment of NH(2-C₅H₄N)₂ with [AlH₃(NMe₃)] yielded the six-co-ordinate complex [Al{N(2-C₅H₄N)(2-C₅H₄N)} ₃], the crystal structure of which confirms it to be monomeric with intramolecular Al-N (aromatic) dative bonds from one pyridyl functionality of each amide ligand. In solution this complex exhibits fluxional behaviour which has been investigated by variable-temperature ¹H NMR spectroscopy.