ABSTRACT Arylnitrenes are highly reactive intermediates whose chemistry is governed by spin state, electronic structure, and perturbations of aromatic stabilization within the phenyl ring. Although their formation and reactivity have been extensively studied, their electronic spectroscopy has received significantly less attention. In this study, investigation of the photochemical generation of a matrix‐isolated arylnitrene, 2,6‐dichloro‐4‐hydroxyphenylnitrene, from the corresponding aryl azide revealed an unusually structured long‐wavelength absorption band. Infrared and UV–Vis spectroscopy, supported by calculations, showed that this feature arises from vibronic coupling between a formally forbidden electronic transition and a specific normal mode, rendering the transition observable. Magnetic response analyses (NICS, ACID, and GIMIC) indicated that both the singlet and triplet arylnitrenes retain aromatic stabilization, with the triplet state exhibiting enhanced magnetic delocalization and diatropic ring currents extending onto the nitrene nitrogen. These results highlight vibronic coupling and aromaticity as key factors governing arylnitrene photophysics.
Joshi et al. (Fri,) studied this question.