AbstractThe radical cat ions of styrene (π‐type), generated by photosensitized electron‐transfer of 1,4‐dicyanobenzene (DCB), using 2‐methyl‐2‐nitrosopropane (MNP) as spin trap ping agents and nucleophiles as the co‐reactant were investigated. The spin‐trapped nitroxide radicals were subjected to HPLC‐ESR and mass spectroscopic studies. Long‐range hfsc were obtained by resolution enhancement. Mass spectral fragmentation pat terns sup port the regioselective formation of the trapped nitroxides, which is derived from theanti‐Markovnikov addition of the methanol to the β‐position of t