| Abstract
| - The reactive intermediates N,N-di(4-chlorophenyl)nitrenium ion and N,N-di(4-bromophenyl)nitreniumion were generated through photolysis of the corresponding N-amino(2,4,6,-collidinium) ions. The behaviorof these diarylnitrenium ions was characterized by laser flash photolysis, analysis of the stablephotoproducts, and ab initio calculations with density functional theory. The latter predict thesespecies to have singlet ground states. The halogenated diarylnitrenium ions are significantly longerlived than the unsubstituted diphenylnitrenium ion. Specifically, cyclization to form carbazole derivativesoccurs negligibly, if at all, with the halogenated derivatives. They do, however, carry out most of thecharacteristic reactions of singlet arylnitrenium ions, including combining with nucleophiles on thearyl rings, adding to arenes, and accepting electrons from readily oxidized traps. Interestingly thesespecies also abstract H atoms from 1,4-cyclohexadiene and various phenol derivatives. The implicationof the latter process in relation to the computed singlet−triplet energy gaps of ca. −12.5 kcal/mol isdiscussed.
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