Photodisproportionation of (1,5-Cyclooctadiene) copper(I) Hexafluoroacetylacetonate Induced by Metal-to-Ligand Charge Transfer Excitation

The complex CuI(COD)(hfac) with COD = 1,5- cyclooctadiene and hfac = hexafluoroacetyl-acetonate shows two long-wavelength absorptions at λmax = 308 and 241 nm which are assigned to hfac intraligand (IL) and CuI →COD metal-to-ligand charge transfer (MLCT) transitions, respectively. The photolysis of CuI(COD)(hfac) in hexane leads to the release of the olefin and the subsequent disproportionation of CuI(hfac) to elemental copper and CuII(hfac)2 with the quantum yields Φ = 10−3 at λirr =313 nm and Φ = 3×10−3 at λirr = 254 nm. It is suggested that the reactive excited state is of the MLCT type.