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

While (Ph 2 CN 2 )B(C 6 F 5 ) 3 is unstable, single electron transfer from Cp* 2 Co affords the isolation of stable products [Cp* 2 Co][Ph 2 CNNHB(C 6 F 5 ) 3 ] 1 and [Cp*Co(C 5 Me 4 CH 2 B(C 6 F 5 ) 3 )] 2 . The analogous combination of Ph 2 CN 2 and BPh 3 showed no evidence of adduct formation and yet single electron transfer from Cp* 2 Cr affords the species [Cp* 2 Cr][PhC(C 6 H 4 )NNBPh 3 ] 3 and [Cp* 2 Cr][Ph 2 CNNHBPh 3 ] 4 . Computations showed both reactions proceed via transient radical anions of the diphenyldiazomethane–borane adducts to effect C−H bond activations.