Iminocyclohexadienyl cations

It is now apparent that nitrenium ions occur in a variety of contexts including the so-called Bamberger rearrangement (i.e., acid-catalyzed isomerization of N-hydroxyaniline 14 to 4-aminophenol 15, Fig. 13.9), and the aforementioned catabolism of arylamines. The earlier workers, however, for the most part did not explicitly consider the possibility of such a species. Heller et al. were the first to present kinetic evidence for such an intermediate. Interestingly, they chose to represent it as the iminocyclohexadienyl cation (16), With the customary ellipsis of allowing a single valency structure to represent mesomeric systems. ... 

Srivastava, S., Toscano, J. R, Moran, R. J., and Falvey, D. E., Experimental confirmation of the iminocyclohexadienyl cation-like structure of arylnitrenium ions time-resolved IR studies of diphenylnitrenium ion, J. Am. Chem. Soc., 119, 11552, 1997. 

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