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

摘要

The photolysis of Fe~(III)(et_2dtc)_3 with et_2dtc~- = diethyldithiocarbamate in inert solvents (e.g., CH_3CN) and in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) leads to the formation of Fe~(II)(et_2dtc)_2(dppe) and (et_2dtc)_2 = tetraethylthiuramdisulfide. At equimolar concentrations (2.76 X 10~(-5) M) of Fe~(III) (et_2dtc)_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_2dtc)_2 and a et_2dtc radical in the primary photochemical step. Product formation occurs by the interception of Fe~(II)(et_2dtc)_2 with dppe.