A Three-Membered Diazo-Aluminum Heterocycle to Access an Al=C π Bonding Species

[1+2] cycloaddition between a cyclic (alkyl)-(amino)aluminyl anion (3) and diaryldiazomethane affords an AlN2 three-membered ring species (4). Compound (4) is thermally unstable and spontaneously releases N-2 gas under the mild reaction condition to generate an ion-separated species 5. An X-ray study shows that the anionic part of 5 bears a considerable short exocyclic Al-C bond, and computational studies involving molecular orbital and natural bond orbital analysis indicate the A1=C pi bonding character. The Al=C moiety of 5 undergoes intramolecular C-H activation. Moreover, reaction of 5 with a diazo compound leads to the reduction and complete cleavage of the N=N double bond.

Automated summary

The [1+2] cycloaddition reaction between a cyclic (alkyl)-(amino)aluminyl anion and diaryldiazomethane results in the formation of an AlN2 three-membered ring species, which shows interesting reactivity and properties.