C-H Bond Activation by Radical lon Pairs Derived from R_3P/Al(C_6F_5)3 Frustrated Lewis Pairs and N_2O

摘要

Al(C_6F_5)_3/R_3P [R = tert-butyl (tBu), mesityl (Mes), naphthyl (Nap)] frustrated Lewis pairs react with N_2O to form species having the formula R_3P(N_2O)A1(C_6F_5)_3, which react with additional alane to generate proposed frustrated radical ion pairs formulated as [R_3P·][(μ-O·)(Al(C_6F_5)_3)_2] that can activate C-H bonds. For R = tBu, C-H activation of a tBu group affords [tBu_2PMe(C(CH_2)Me)][(μ-OH)(Al(C_6F_5)_3)_2]. In the case of R = Mes, the radical cation salt [Mes_3P·][(μ-HO)(A1(C_6F_5)_3)_2] is isolated, while for R = Nap, the activation of toluene and bromobenzene gives [(Nap)_3PCH_2Ph][μ-OH)(Al(C_6F_5)_3)_2] and [(Nap)_3PC_6H_4Br] [μ-HO)(A1(C_6F_5)_3)_2], respectively.