Decarbonylation of the 2-hydroxypyridine radical cation: A computational study

The potential energy surface (PES) for the dissociation of the 2-hydroxypyridine (2-HP) radical cation was determined from G3//B3LYP calculations, including the loss of CO, HCN, and HNC. The formation of the 1Hpyrrole radical cation by decarbonylation through a more stable tautomer, the 2-pyridone (2-PY) radical cation, was the most favorable dissociation pathway. Kinetic analysis by the Rice-Ramsperger-Kassel-Marcus model calculations was carried out based on the obtained PES. It is proposed that the dissociation occurs after a rapid tautomerization to 2-PY⁺, and that most of the ions generated by ionization of 2-HP have the structure of 2-PY⁺ at equilibrium above the tautomerization barrier.