ESR Study of Irradiated Pyridine

Abstract

Pyridine and pyridine‐d₅ were irradiated with electrons in the solid state at −196°C. After the irradiation, ESR spectra were measured over a temperature range from −196°C to their melting points. For pyridine, a triplet spectrum (separation of 30 G) with a quartet substructure (separation of 4.3 G) was observed at −196°C. It was assigned to cation radicals [Complex chemical formula] The triplet spectrum disappeared at elevated temperatures and an eight‐line spectrum (separation of 12 G) was observed at −90°C which was assigned to free radicals [Complex chemical formula] After the disappearance of these radicals at −65°C, a singlet spectrum (ΔH_msl of 15 G) was observed and disappeared at about −50°C. It was assigned to pyridyl radicals. The radicals produced in the irradiated pyridine‐d₅ had the same nature as those observed in irradiated pyridine.