Substituent effect on the oxidation of azaferrocene studied by 1H NMR and 57Fe Mössbauer spectroscopy

The substituent effect on the oxidation site of azaferrocene was studied by using 1H NMR and 57Fe Mössbauer spectroscopy. An introduction of methyl substituent to the cyclopentadienyl ring promotes the oxidation of the central iron atom of azaferrocene more than the nitrogen atom in pyrrole ring, which is contrary to the introduction of methyl substituent to the pyrrole ring. Broadening and shift of NMR signals were observed by successive adding of iodine into the 1′,2,2′,3′,4′,5,5′-heptamethylazaferrocene and then narrowing was observed by further adding of iodine, suggesting a structural change by iodine oxidation.