Hydrogen Atom Transfer: An Intramolecular Main‐Group Metal‐Ligand Cooperative Biradical Pathway

Comprehensive Summary Redox‐active ligands on transition metals have been shown to provide access to biradical reaction pathways, however the corresponding reaction pathway for main group systems is not known. The compound ((2,6‐ i Pr 2 C 6 H 3 )NC(Me)) 2 AlCl(THF) 1 reacts with aldehyde or ketone effecting SET and prompting C−C coupling to afford diradical products. However, the corresponding reactions with 2,2,6,6‐tetramethylpiperidine‐ N ‐oxide, azides and diazomethanes proceed to give products derived from both single electron transfer (SET) and hydrogen atom transfer (HAT). Computations show that these latter products are formed via initial SET affording a biradical intermediate which prompts HAT.