PHOTOREDOX BEHAVIOR OF CHLOROCOPPER(II) COMPLEXES IN ACETONITRILE - MECHANISM AND QUANTUM YIELDS

Visible anaerobic irradiation of the system CuCl2LiCl in acetonitrile leads to the formation of Cu(I) with quantum yields Φ in the range 0.04-0.13, which decrease with time and depend on the [Cu(II)]/[Cl-] ratio. The higher this ratio, the higher the Φ values are. The aerobic quantum yields are much smaller and the air quenching effect is more pronounced for the more chlorinated Cu(II) species. Only the Cu(I)Cl bond appears to be sensitive to molecular oxygen, the Cu(I) being re-oxidized during the time interval required for the photoproduced chlorocopper(I) species to be fully solvated. From pulsed photolysis experiments (using a neodymium laser flashing at 473 nm) it appears that the transient Cl{radical dot}2 (which originates from Cl{radical dot} and free Cl-) is quenched only by Cu(II) (kII = 1.7 × 108 dm3 mol-1 s-1) and Cu(I) (kI = 2.8 × 108 dm3 mol-1 s-1) and not by Li+, Cl- or the solvent. © 1979.