Dioxygen Reactivity of an Iron Complex of 2-Aminophenol-Appended Ligand: Crystallographic Evidence of the Aromatic Ring Cleavage Product of the 2-Aminophenol Unit

Abstract

2-Aminophenol appended pentadentate ligand HGan was synthesized by mixing equimolar amounts of 2-[bis(2-pyridylmethyl)aminomethyl]aniline (A) and 3,5-di-tert-butyl catechol in hexane in the presence of EtN under air. The ligand reacted with Fe(ClO)·6HO or Fe(ClO)·6HO in the presence of tetrabutylammonium perchlorate, and EtN under air and provided a μ oxo-bridged dinuclear iron complex (1). X-ray single-crystal analysis of complex 1 revealed the presence of a furan derivative, resulting from the oxidative aromatic C-C bond cleavage product of 2-aminophenol derivative, in the coordination sphere of each iron center. Mechanistic investigation for the formation of complex 1 established that in the absence of molecular oxygen no oxidation of the appended 2-amidophenolate unit took place. An iron(III)-amidophenolate complex, formed initially, further reacted with molecular oxygen and caused oxidative aromatic C-C bond cleavage via a putative alkylperoxo species.

Tuning the stereoelectronic factors of iron(ii)-2-aminophenolate complexes for the reaction with dioxygen: oxygenolytic C–C bond cleavage vs. oxidation of complex

“…However, Mukherjee and coworkers have shown an example of an iron complex of 2-aminophenol-appended supporting ligand where reaction with dioxygen resulted in a dimeric iron(III) μ 2 oxo-bridged complex coordinated by a furan derivative in each metal unit, which was proposed to be formed as a result of the oxidative aromatic C-C bond cleavage product of 2-aminophenol. 58 Scheme 7 Proposed mechanism for the reaction of 4 and 5 with dioxygen.…”

Synthesis of Cu(II) complexes by N,O‐donor ligand transformation and their catalytic role in visible‐light‐driven alcohol oxidation

“…[ 1–6 ] It has been also noticed that in a sterically demanding situation or for the sake of less strainer chelating environment, certain ligands can decyclise or ring‐opening of the ligands can happen. [ 7–15 ] In point of view of the catalytic properties, in‐built flexibility of the associated ligands in terms of denticity, ability to engage in different noncovalent interactions with substrate, and providing an efficient and robust platform remain very crucial as per earlier reports. [ 16–21 ] Among various catalytic activities, aerobic oxidation of primary alcohol is an important subclass of catalytic reaction in terms of biological as well as industrial viewpoint.…”