10.1021/ic061463u.s003 Jianfeng Li Jianfeng Li Bruce C. Noll Bruce C. Noll Charles E. Schulz Charles E. Schulz W. Robert Scheidt W. Robert Scheidt New Insights on the Electronic and Molecular Structure of Cyanide-Ligated Iron(III) Porphyrinates American Chemical Society 2007 microcrystalline form EPR spectra core conformation EPR spectroscopy measurement M össbauer spectroscopy Molecular Structure bi New Insights TMP state change cm cyanide ligands Fe electron configuration splitting values range energy difference porphyrin ligand complex quadrupole splitting value 2007-03-19 00:00:00 Dataset https://acs.figshare.com/articles/dataset/New_Insights_on_the_Electronic_and_Molecular_Structure_of_Cyanide_Ligated_Iron_III_Porphyrinates/3018292 The preparation and characterization of several new cyano-ligated six-coordinate low-spin iron(III) porphyrinates are reported. The synthesis and structure of the new bis(cyanide) derivative K(222)][Fe(TMP)(CN)<sub>2</sub>] (TMP = tetramesitylporphyrinate) is described. Three mixed-ligand species of the general form [Fe(Porph)(CN)(L)], where L = 1-methylimidazole or pyridine, have also been prepared and structurally characterized. All complexes have been studied with EPR spectroscopy in frozen solution and in microcrystalline form. In some cases, especially those of the bis(cyanide) derivative above and the previously reported [Fe(TPP)(CN)<sub>2</sub>]<sup>-</sup>, there are significant differences in the EPR spectra as a result of the state change. These spectral differences can be correlated with changes in the electron configuration that are the likely result of a differing environment of the coordinated cyanide ligands; the core conformation and electronic structure of the porphyrin ligand are unlikely to play a role. All four new complexes and [Fe(TPP)(CN)<sub>2</sub>]<sup>-</sup> have been studied by Mössbauer spectroscopy with variable-temperature and applied magnetic-field measurements. The sign of the quadrupole splitting value has been established as negative. These measurements have allowed us to give estimates of the energy difference between the two close-lying d<sub>π</sub> (d<i><sub>xz</sub></i> and d<i><sub>yz</sub></i>) orbitals. These splitting values range from ∼267 cm<sup>-1</sup> for [Fe(TPP)(CN)<sub>2</sub>]<sup>-</sup> to ∼614 cm<sup>-1</sup> for [Fe(TPP)(CN)(Py)].