Moessbauer study of (2-nitrosopropane)(N-methylimidazole) and (2-nitrosopropane)(isopropylamine) iron (II) tetraphenylporphyrins

Two iron-tetraphenylporphyrin complexes TPPFe(iPrNO)(NMe Imid) and TPPFe(iPrNO)(iPrNH2) have been studied by Moessbauer spectroscopy between 300 and 4.2 K and with applied magnetic fields up to 6 T at 4.2 K. The observed Moessbauer parameters are consistent with the presence of a low spin Fe(II) state in these complexes. However magnetic susceptibility measurements and the hyperfine magnetic field value Hsub(hf) show evidence for a weak paramagnetism. The Moessbauer data of these two complexes are similar to those reported for the oxygenated complex TPFe(O2)(NMe Imid), suggesting a good analogy between the coordinating ability of the O2 and RNO ligands. (orig.)