MULTIPLE BONDS BETWEEN MAIN-GROUP ELEMENTS AND TRANSITION-METALS .144. PHOTOREACTIVITY OF ORGANORHENIUM(VII) OXIDES

Ligand-to-metal charge transfer excitation of organorhenium(VII) oxides R-ReO3 [R = CH3, C2H5, eta(1)-mesityl, C6H5, eta(5)-C5H5, eta(5)-C5H4(CH3), and eta(5)-C-5(CH3)(5)] in acetonitrile or dichloromethane solution leads to photoredox decomposition. It is shown by EPR spectroscopy that radical pairs R(.)/(ReO3)-Re-. are generated in the primary step. The overall efficiency is determined by the reactivity of the radicals R(.), which decreases in the order CH3 > C2H5 > mesityl > C5H5 > C5H4(CH3) > C-5(CH3)(5). The regeneration of R-ReO3 is favored with increasing stability of R(.). Accordingly the quantum yield varies with R.