X-ray Photoelectron Spectroscopic Studies on Monomeric and Dimeric Iron Porphyrins

The Fe 2p3/2 and N Is X-ray PES binding energies for the dimeric iron porphyrin complexes µ-nitrido-bis[α,β,γ,δ-tetraphenylporphinatoiron] and g-oxo-bis[α,β,γ,δ-tetraphenylporphinatoiron] are reported. In addition, X-ray PES binding energies for the monomeric α,β,γ,δ-tetraphenylporphinatoiron cation with selected anions (CIO4-, Br-, Cl-, and N3-) are found to be correlated with the half-wave potentials for reduction in the noncoordinating solvent dichloromethane. Comparisons are made between the previously reported infrared, Mossbauer, X-ray crystallographic, magnetic susceptibility, and electrochemical results and the X-ray PES data in an attempt to unambiguously assign the electron environment of the µ-nitrido complex. In contrast to the µ-oxo dimer and the monomers, the electronic configuration about each five-coordinate Fe atom in the µ-nitrido dimer has been shown to be low spin.