Electrochemically probing the correlation between photo-induced CO-releasing behaviours and their LUMO energies of three diiron carbonyl complexes

Three diiron carbonyl complexes with different carbonyl ligands have been synthesized. Pentacarbonyl and tetracarbonyl complexes 2 and 3 were prepared by the substitution of the bound CO of complex 1 by PPh 3 . The photo-induced CO-releasing behaviours of these complexes correlate linearly to their reduction potentials and further to the energy level of their LUMOs. The more negative the reduction potentials, the more reactive the complexes. The photo-induced CO-release can be further promoted when a nucleophile is presented such as thiopronin.