Theoretical evidence favoring true iron(V)-oxo corrole and corrolazine intermediates

Although many formally FeV intermediates are known in the form of peroxidase compound I intermediates and their synthetic models, "true" d3 FeVO intermediates have remained elusive and hence a Holy Grail of sorts for many bioinorganic chemists. Very recently, Newcomb and co-workers provided transient absorption spectroscopic evidence suggestive of FeVO corrole intermediates. Here, we report DFT calculations predicting nearly isoenergetic FeVO and FeIVO corrolato2-* states for Fe(corrolato)(O) intermediates. In the course of a theoretical search for systems in which a true FeVO state might be favored by a clear and substantial margin of energy, we have identified corrolazine as a promising supporting ligand; thus, we find that with corrolazine, the FeVO states are favored by at least 0.5 eV over FeIVO corrolazinato2-* states.