Lewis Acid‐Mediated One‐Electron Reduction of Nitrous Oxide

The one‐electron reduction of nitrous oxide (N2O) was achieved using strong Lewis acids E(C6F5)3 (E=B or Al) in combination with metallocenes. In the case of B(C6F5)3, electron transfer to N2O required a powerful reducing agent such as Cp*2Co (Cp*=pentamethylcyclopentadienyl). In the presence of Al(C6F5)3, on the other hand, the reactions could be performed with weaker reducing agents such as Cp*2Fe or Cp2Fe (Cp=cyclopentadienyl). The Lewis acid‐mediated electron transfer from the metallocene to N2O resulted in cleavage of the N−O bond, generating N2 and the oxyl radical anion [OE(C6F5)3]⋅−. The latter is highly reactive and engages in C−H activation reactions. It was possible to trap the radical by addition of the Gomberg dimer, which acts as a source of the trityl radical. Lewis acids E(C6F5)3 (E=B, Al) activate nitrous oxide towards one‐electron reduction by metallocenes, generating oxyl radical anion intermediates that can perform C−H activation and radical coupling reactions.