Low-temperature EPR study of radical cations of vinyl ethers in a Freon matrix

Using low-temperature EPR the transformations of radical cations of aliphatic vinyl ethers radiolytically generated in a Freon matrix have been investigated. Three-line spectra found at 77 K [hfs constants of 1.5 mT (1H) and 2.2 mT (1H)] and at 95 K [1.9–2.1 mT (2H)] were attributed to the radical cation. A quartet was observed at 130 K, usually with binomial intensities [hfs constants of 1.3 mT (3H)] and a triplet [1.7–1.9 mT (2H)] was found after cooling samples back to 95 K. The conversion of the quartet to the triplet was found to be thermally reversible and both spectra are assigned to different states of a (distonic) dimer cation.