Other redox and protonation tests were used as well. Electrochemical oxidation of 2 is irreversible under the same CV conditions used for 4 (Figure ). To test whether 4 could be protonated, it was treated with one equiv of [H(OEt2)2][BF4] in THF. A dark brown solid precipitated from the reaction mixture, and the IR spectrum of the solid showed a single N-H stretch at 3250 cm -1 , which is much lower than the N-H stretching frequency of 2 at 3336 cm -1 .