Photolysis of organoiron arene complexes.

Photolytic demetallation of cyclopentadienyliron complexes was investigated. Effects of solvent nucleophilicity, counter anion, wavelength, and nature of the arene were studied. Initial results indicate a dependence on the wavelength of the light source as well as the duration of photolysis, with degrdn. of the org. backbone occurring with longer photolysis times. For example, two complexes (I and II) were demetallated at different wavelengths. Cleavage of the iron moieties from the org. backbone at 300 nm was obsd. after 15-30 min, while the use of simulated sunlight required 1-3 h. At 300 nm, increasing the duration of photolysis from 30 min to 8 h reduced the yield from 20% to 4% for compd. I and from 80% to 60% for compd. II. Addnl., the NMR spectra of the 300 nm demetallation products of II showed a change in the arom. protons resonating between 6.85 ppm and 7.0 ppm from 1-8 h.