The compound LiAl(N : CBut2)4, prepared from AlCl3+ 4 But2C : NLi, has been shown by X-ray diffraction to contain an aluminium atom surrounded by a distorted tetrahedron of di-t-butylmethyleneamino-groups, two terminally attached, with the near-linear C : NAl skeletons and short Al–N distances appropriate for appreciable N⇌Al (p→d) dative π-bonding, the other two bridging the aluminium to the lithium, which is also apparently involved in a novel type of Li ⋯ H–C interaction.