PHOTOREACTIVITY OF MO(CN)(8)(3-) ION - PHOTOREDOX AND PHOTOSUBSTITUTION PROCESSES

The photochemical reactions of the Mo(CN)(8)(3-) ion, induced by excit ation within the lowest energy ligand-to-metal charge transfer (LMCT) band (lambda(cx) 365 nm), were studied in aqueous solutions. The detec tion of OH radicals strongly supports the intermolecular photoredox pr imary step leading to the formation of Mo(CN)(8)(4-) and photo-oxidati on of the solvent. The efficient photoredox process (Phi(r)=0.8+/-0.02 ) is concomitant with a photosubstitution reaction (Phi(s)=0.2) follow ed by the pH-dependent fast thermal reduction of the substrate by both photosubstitution products, i.e. CN- and Mo(CN)(7)OH22- ions. A schem e of photochemical and thermal reactions is given and the results are compared with those for the W(CN)(8)(3-) complex.