Are Aroylnitrenes Ground-State Singlets? Photochemistry of β-Naphtoyl Azide

Article abstract of DOI:10.1021/ja00253a037

Both direct-irradiation and triplet-sensitized photolyses of β-naphtoyl azide (BNA) give nitrene-derived products indicative of reaction only from the singlet state of β-naphtoylnitrene (BNN).The triplet nitrene is not detected in chemical trapping or spectroscopic experiments, which readily reveal related intermediates.The results require that the energy of singlet BNN be very close to or below the energy of triplet BNN.The data are most consistent with a singlet ground state for BNN.A qualitative perturbation molecular orbital approach is used for this surprising finding.