PHOTOCHEMISTRY AND PHOTOPHYSICS OF TRANS-D2-DIOXO COMPLEXES OF OSMIUM(VI)

Trans-[OsVI(L)(O)2](ClO4)2 (where L = 14TMC, 15TMC, 16TMC, CRMe3) and trans-[OsVI(CN)4(O)2](Ph4As)2 complexes display vibronic structured spin-allowed and spin-forbidden transitions at 300-320 and 345-370nm. The 3[(dxy)1(dπ*)1] excited states of trans-dioxoosmium(VI) are emissive and long-lived [lifetimes 0.4 to 1.6μs] both in solid state and in fluid solutions. For rans-[OsVI(14TMC)(O)2]2+, the OsO bond in the 3[(dxy)1(dπ*)1] state is ca. 0.063Å longer than in the ground state. Trans-dioxoosmium(VI) complexes function as a powerful one-electron oxidant with E(OsVI*/OsV) ranging from 1.1 to 2.3V vs. N.H.E. Photo-induced oxygen atom transfer reactions have been observed with trialkylphosphines, dialkylsulphides, and alkenes. © 1990.