Photochemistry of Oxirane-Derived Radical Cations in Freonic Matrices at 77 K

The data on the structure and the features of the photochemical reactions for radical cations (RCs) derived from various oxiranes (epoxides) that can be stabilized in Freon matrices at 77 K are summarized. The nature of the RCs and the products of their photochemical transformations have been determined via quantum chemistry, electron paramagnetic resonance (EPR) and low-temperature UV/Vis spectroscopy. For the RCs, it is shown that, depending on the structure of the precursor molecule, transitions between their ring-open and ring-closed forms, deprotonation reactions affording C-centered radicals and more complex transformations can take place when exposed to light. Possible explanations of the observed effects are discussed.