Single Electron Transfer to Diazomethane-Borane Adducts Prompts C-H Bond Activations.

While (Ph2 CN2 )B(C6 F5 )3 is unstable, single electron transfer from Cp*2 Co affords the isolation of stable products [Cp*2 Co][Ph2 CNNHB(C6 F5 )3 ] 1 and [Cp*Co(C5 Me4 CH2 B(C6 F5 )3 )] 2. The analogous combination of Ph2 CN2 and BPh3 showed no evidence of adduct formation and yet single electron transfer from Cp*2 Cr affords the species [Cp*2 Cr][PhC(C6 H4 )NNBPh3 ] 3 and [Cp*2 Cr][Ph2 CNNHBPh3 ] 4. Computations showed both reactions proceed via transient radical anions of the diphenyldiazomethane-borane adducts to effect C-H bond activations.