This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Iridium(III) complexes with the 5,10,15-tris-pentafluorophenylcorrole anion (tpfc) represent the most thoroughly characterized examples of 5d metal-corrole complexes since their discovery in 2008, but the electronic and molecular structures of their oxidized derivatives remain largely mysterious. We have strong evidence from EPR and visible spectroscopy that iridium(III) corroles, unlike their 3d cobalt analogues, form paramagnetic M(IV) complexes upon reaction with a single oxidizing equivalent. In fact, we found that cobalt(III) corroles appear to be oxidized at the ligand, iridium(III) corroles at the metal, and rhodium(III) corroles in some delocalized fashion. However, we still have serious questions about the level of covalency in these complexes, the amount of non-innocence demonstrated by the corrole ligand, the ligand field structure of the compounds, and the nature of Group 9 metallocorroles which have been subjected to double oxidation. We hope to use the edge positions of our complexes to determine the oxidation states of the central ion and the levels of electronic delocalization onto the ligand. We also propose the collection of EXAFS data for all oxidized complexes in order to probe the local structure around the metal ions, since crystallographic data on these compounds has not been forthcoming. We have gathered preliminary data on our iridium complexes showing that EXAFS-derived bond lengths coincide accurately with crystallographic parameters, and that the LIII-edge spectrum is highly sensitive to the oxidation state of the metal. We wish to improve upon this data by taking spectra of powdered samples in transmission mode, now that we have developed a methodology to produce larger amounts of corrole. More importantly, we will execute fine control over the oxidation states of the complexes in our next run using a known spectroelectrochemical setup at SSRL. These changes should allow us to gather high quality data on the structures of metallocorroles.
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