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Quantum Chemical Analysis of Heteroarylnitrenium Ions and Mechanisms for Their Self-Destruction
journal contribution
posted on 2000-05-27, 00:00 authored by Michael B. Sullivan, Christopher J. CramerSinglet−triplet state-energy splittings in arylnitrenium ions are substantially reduced when the aromatic
system is heterocyclic with nitrogen atoms incorporated at ring positions that would otherwise better stabilize
the formally exocyclic positive charge through resonance. Ring contraction rearrangements of singlet
arylnitrenium ions with a nitrogen atom at an ortho position are predicted to proceed with barrier heights that
become lower with increasing substitution of nitrogen atoms at other positions. Predilection to delocalize positive
charge also controls the relative facility with which (i) N-acetylarylnitrenium ions undergo ring closure to
form 2-oxazolium cations and (ii) arylnitrenium ions are subject to nucleophilic aromatic substitution by water.