116632-28-1Relevant articles and documents
An Oxygen-peri-Bridged Quinolinium Cation and Its Monoradical Counterpart
Kotha, Raghavendhar R.,Nash, John J.,Kentt?maa, Hilkka I.
, p. 1407 - 1412 (2017)
Generation of a σ,σ,π-triradical was attempted by collision-activated dissociation (CAD) of two iodine atoms and an NO· radical from 2,4-diiodo-5-nitroquinolinium cation in an ion trap mass spectrometer. However, the reactivity of the product was consistent with a monoradical rather than a triradical. The mechanism of its formation was explored. In the first CAD step, an iodine atom is lost to generate the 2-iodo-5-nitro-4-dehydroquinolinium cation. Quantum chemical calculations suggest that in the second CAD step, the radical site at C-4 adds to the adjacent NO2 group followed by loss of NO· to generate the 2-iodo-4-oxyl-5-dehydroquinolinium cation. Calculations also suggest that in the third CAD step, this cation cyclizes to form an oxygen-peri-bridged 2-iodoquinolinium cation that then loses the remaining iodine atom to generate a distonic 4,5-oxygen-peri-bridged 2-dehydroquinolinium cation. For the analogous 4-oxyl-5-dehydroquinolinium cation, the cyclization is calculated to be exoergic by 8.7 kcal mol–1, with a free energy barrier of 14.0 kcal mol–1. The cyclized product is the first experimentally observed oxygen-peri-bridged naphthalene derivative. It displays low reactivity. However, it's monoradical counterpart is highly reactive and undergoes typical radical reactions.
