Aluminylene

[3][4][5] The first free aluminylene came from Tuononen and Power, who used bulky terphenyl ligands to stabilize the reduction of the aluminium(III) diiodide.

[8]  Both free aluminylenes largely depend on the steric bulk of their ligands for kinetic protection, a common motif in stabilizing reactive main group complexes.

[11] The N-aluminylene reported by Liu and coworkers was shown to undergo an oxidative insertion reaction when mixed with IDippCuCl (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to form a terminal copper-alumanyl complex.

[9][12] In 2023, Liu and coworkers published further examples of the reactivity of their N-aluminylene as they attempted to react the compound with various boron based Lewis acids.

This free alumaborane was characterized via 11B NMR and showed two three-coordinate boron atoms, an observation further supported by x-ray crystallography data.

[15][16] However, in 2022 Liu and coworkers were able to form an adduct between their N-aluminylene and an NHC, a combination that demonstrated increased reactivity compared to the free aluminylene.

They explained this with Density Functional Theory calculations at the M06-2X/def2-SVP level showing that the NHC coordination narrowed of the HOMO-LUMO gap by raising the energy of the aluminium lone pair (HOMO).

Intrinsic Bond Orbital calculations showed a significant degree of pi-backbonding from the aluminylene in the tungsten and chromium complexes, which added further stabilization.

The general structure of an aluminylene compound.
Synthetic method behind and structure of the terphenyl aluminylene synthesized by Power and coworkers.
Synthetic scheme for the N-aluminylene.
Synthesis of an Al-N triple bond compound from an aluminylene precursor.
Synthetic scheme of the terminal copper alumanyl complex from the N-aluminylene.
Example syntheses and structures of aluminium heterocycles from unsaturated hydrocarbons using the N-aluminylene.
Synthetic scheme and structure of the N-aluminylene reacting with a boron lewis acid.
Synthetic scheme for one of Tokitoh's methods of forming aluminylene-platinum compounds.
Synthetic scheme for transition metal complexes formed by coordination to an N-aluminylene.