Reagent‐Regulated Oxidative O ‐Demethylation of a Ferrous Complex Stabilized by a Tetradentate N Ligand with a Methoxyphenyl Substituent

A ferrous complex Fe II L OMe Cl 2 , 1 , where L OMe is 2‐methoxy‐ N , N ‐bis(pyridin‐2‐ylmethyl) aniline, has been synthesized and studies on its structure, spectral properties, and reactivity have been carried out. The complex has rich spectral properties and shows a well‐defined paramagnetic 1 H NMR spectrum with sharp and hyperfine shifted signals, which were assigned with the help of a combination of 1 H– 1 H COSY and T 1 and T 2 relaxation time measurements. Though stable to air, complex 1 underwent oxidation in the presence of AgClO 4 , which resulted in the formation of a symmetric diferric oxo complex [(L OMe Fe III Cl) 2 O](ClO 4 ) 2 , 2 . However, on reaction with strong oxidants such as t BuOOH, complex 1 yielded a mixture of an unsymmetric diferric oxo complex L OMe Fe III ClOFe III Cl 3 , 3 , and a mononuclear ferric complex L O– Fe III Cl 2 , 4 , with a modified phenoxide ligand L O– , which is formed as a result of the demethylation of L OMe during oxidation. The factors affecting O ‐demethylation were studied and a possible mechanistic pathway involving a high‐valent iron‐oxo species is proposed.