Would you think that the complex is stable enough for time-resolved X-ray absorption measurements? Like that in the Majed Chergui lab: http://lsu.epfl.ch/Research
Ferrooxalate ([Fe(ox)3]3-) is used as an actinometer for light sources. You need only a UV-VIs photometer and phenantroline to quantify the progress of the photoreaction
We quantified the iron by this methode but now we need to identify and to quantify the various species produced during the photo-transformation of this complex