Nature Chemistry 2, 853–857 (2010); published online 8 August 2010; retracted after print 29 June 2017.

We the authors are retracting this Article as we are unable to explain the presence of data in three of the spectra; namely, Figure 2a (hemin in ethanol) and Figure 2c ([Fe(bpy)3]2+ in water and in acetonitrile). The spectra in Figures 2a and 2c feature data in the 730 eV to 735 eV region that appear to have been duplicated from other regions of the spectra. We are unable to provide raw data for this region for any of the three spectra and we are unable to attempt to reproduce the spectra under the same conditions originally reported because the original beamline (U41-PGM) that we have used to conduct these experiments has been dismantled. The data integrity issues undermine our full confidence in the integrity of the study and we therefore wish to retract the Article.