Understanding reactivity patterns of the dialkylaniline radical cation

N,N-Dimethylaniline and N, N-diethylaniline react with Cu2+ to form the corresponding amine radical cations. The radical cations were characterized by their absorption spectra. In the absence of any nucleophiles, the radical cations dimerize to give tetraalkylbenzidines, and this reaction can be monitored by absorption spectroscopy. In the presence of nucleophiles such as Cl-circle minus, Br-circle minus, or SCN circle minus, the radical cations undergo nucleophilic substitution to give para-substituted dialkylanilines in good yields.