Photochemistry of tris(diethyldithiocarbamato)iron(III). Reduction to a stable iron(II) complex induced by ligand-to-metal charge transfer excitation

The photolysis of Fe-III (et(2)dtc)(3) with et(2)dtc(-) = diethyldithiocarbamate in inert solvents (e.g., CH3CN) and in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) leads to the formation of Fe-III (et(2)dtc)(2)(dppe) and (et(2)dtc)(2) = tetraethylthiuramdisulfide. At equimolar concentrations (2.76 x 10(-5) M) of Fe-III (et(2)dtc)(3) and dppe the quantum yields are phi = 0.007 at lambda(irr) = 333 nm and 0.003 at 436 nm. This photoreaction, which is initiated by ligand-to-metal charge transfer excitation, generates Fe-II(et(2)dtc)(2) and a et(2)dtc radical in the primary photochemical step. Product formation occurs by the interception of Fe-II (et(2)dtc)(2) with dppe. (C) 2002 Elsevier Science B.V. All rights reserved.