Nitrogen‐Based Lewis Acids Derived from Phosphonium Diazo Cations

Abstract

Reaction of PPh and [(p-ClC H )N ][BF ] affords [(p-ClC H )N(PPh )N(PPh )][BF ] 1, while reaction with (Ph PCH ) gave [(p-ClC H )(NPh PCH ) )][BF ] 2. These species confirm the Lewis acidity of [(p-ClC H )N (PR )][BF ] cations at N. In contrast, use of bulky phosphines afford the species [ArN (PR )][BF ] (R=tBu 3, Mes 4). Compound 3 undergoes one electron reduction to give the stable radical [(p-ClC H )N (PtBu )] 5. Combination of 3 and PtBu acts as an FLP to effect (SPh) cleavage, generating [PhSPtBu ] and the radical [ArN (PR )] . Collectively, these data affirm the ability of the cations [ArN (PR )] to behave as one or two electron acceptors.

Aryldiazonium Salts as Nitrogen‐Based Lewis Acids: Facile Synthesis of Tuneable Azophosphonium Salts

“…[18] Herein, we report on the facile synthesis of readily tuneable azophosphonium salts simply from phosphines and aryldiazonium tetrafluoroborates in acetonitrile,a nd provide detailed mechanistic insight by experimental and computational means.R elated reactions of phenyldiazonium tetrafluoroborate with tertiary amines have also been investigated. [20] As Horner and Stçhr had indicated [13] that compound 1 is unstable both in solution and in the solid state, [10] we resorted to the stronger and sterically more encumbered donor tri-tert-butylphosphine,which, according to DFT calculations at the wB97X-D/ 6-311 + G(d,p) level of theory,s hould provide am ore stable product (DE = À53.2 kcal mol À1 ). 2%; d 31 P{ 1 H} = 43.9 and 52.5 ppm, 3 J P, P = 18.8 Hz), [10] which we tentatively ascribed to the bis-phos- 4 ].…”

Single Electron Transfer to Diazomethane–Borane Adducts Prompts C−H Bond Activations

“…To garner further support for the computed mechanism, efforts to observe the transient radical adducts in the reactions were undertaken, but were unsuccessful. However, monitoring the reaction of (C 12 H 8 )CN 2 , Cp* 2 Fe and Al(C 6 F 5 ) 3 in C 6 H 5 Cl at room temperature by EPR spectroscopy revealed a pentet resonance at g(iso) = 2.0039, with ( 14 N) hyperfine couplings of 3.70 G and 3.58 G. This signal was similar to the related N-based radicals [33] and was attributed to the radical species [Ph 2 CN 2 Al(C 6 F 5 ) 3 ]C À . This signal slowly degrades at room temperature over 5 h, leaving a broad resonance attributed to an organic radical (see Supporting Information).…”

Facile Synthesis of Tuneable Azophosphonium Salts

“…We demonstrate that the σ + para constant correlates well with the colour and spectroscopic properties of a range of azophosphonium salts. This allows facile access to tuneable systems that can be used as dyes or precursors to stable nitrogen‐based radicals …”