Nitrogen‐Based Lewis Acids Derived from Phosphonium Diazo Cations

Reaction of PPh₃ and [(p‐ClC₆H₄)N₂][BF₄] affords [(p‐ClC₆H₄)N(PPh₃)N(PPh₃)][BF₄] 1 , while reaction with (Ph₂PCH₂)₂ gave [(p‐ClC₆H₄)(NPh₂PCH₂)₂)][BF₄] 2 . These species confirm the Lewis acidity of [(p‐ClC₆H₄)N₂(PR₃)][BF₄] cations at N. In contrast, use of bulky phosphines afford the species [ArN₂(PR₃)][BF₄] (R=tBu 3 , Mes 4 ). Compound 3 undergoes one electron reduction to give the stable radical [(p‐ClC₆H₄)N₂(PtBu₃)]^. 5 . Combination of 3 and PtBu₃ acts as an FLP to effect (SPh)₂ cleavage, generating [PhSPtBu₃]⁺ and the radical [ArN₂(PR₃)]^.. Collectively, these data affirm the ability of the cations [ArN₂(PR₃)]⁺ to behave as one or two electron acceptors.