PHOTOREDOX REACTION OF A TRINUCLEAR CO(III), CO(III), RU(II) COMPLEX-INDUCED BY METAL-TO-METAL CHARGE-TRANSFER EXCITATION AND A SUBSEQUENT CHARGE SHIFT

The trinuclear complex H3)5CoIII(mu-NC)CoIII(CN)4(mu-CN)RuIII(CN)53-sh ows a long wavelength absorption near 370 nm which is assigned to a me tal-to-metal charge transfer (MMCT) transition from Ru(II) to the cent ral Co(III) ion. Light absorption by this bands leads to a redox decom position: (NH3)5CoIII(mu-NC)CoIII(CN)4(mu-CN)RuII(CN)53- --> 5NH3 + Co 2+ + CoIII(CN)63- + RuIII(CN)5H2O2-. It is suggested that the initial MMCT transition is followed by a charge shift from the central Co(II) to the cobalt(III) ammine moiety which subsequently undergoes a rapid irreversible decay.