Insights on unimolecular and bimolecular reactivity patterns of pyridyl, pyridyl-N-oxide, and pyridinyl radicals through spin density

Abstract

Spin density is very vital in understanding the thermodynamic stability of radicals, biradicals, etc. To obtain insights on reactivity aspects of radicals using it, we carried out theoretical investigations on the unimolecular and bimolecular reactions of pyridyl1a-c, pyridyl-N-oxide2a-c, and pyridinyl3a-cradical isomers. For all the radicals, we computed the CH bond dissociation energies (BDEs), isomerization reactions through the 1,2-H shift, unimolecular decomposition channels, and the bimolecular reactions with small molecules H2, H2O, CO, CO2, CH4, and CH3OH. Remarkably, spin density at the radical center or the transition state manifested the observed reactivity patterns.