Photolysis of CH3Re(O2)2O induced by ligand-to-metal charge transfer and by peroxide intraligand excitation

The electronic spectrum of the diperoxo complex MeReVII(O2)2O shows a peroxide IL (intraligand) absorption at λmax ∼ 260 nm in addition to the well-known peroxide to Re(VII) LMCT band at λmax = 358 nm. Upon IL excitation, the diperoxo group undergoes a dismutation. Accordingly, MeRe(O2)2O photolyzes to MeReVIIO3 and O2. LMCT excitation at λirr = 405 nm is assumed to generate the radical pair image in the primary photochemical step. Back electron transfer and reaction with water leads finally to the monoperoxo complex MeReVII(O2)O2 and H2O2.