Highly reactive μ-carbido diiron tetraphenylporphine oxo-species: chemical generation and the oxidation ability

Abstract

The multistep interaction of a μ-carbido diiron tetraphenylporphine complex and its imidazole derivative with tert-butylhydroperoxide tBuOOH were investigated in benzene at 298 K by UV–visible, IR spectroscopy and electrochemical study. The kinetics of the stepwise processes were studied and their rate constants k were obtained. The reaction of both non-ligated [FeIVTPP]2C (1) and [ImFeIVTPP]2C (2) with tBuOOH led to high-oxidized species generation following the coordination of a peroxide molecule on the metal center (k 1 = 2.8 M−1s−1) and homolytic cleavage of O–O bond in attached tBuOOH (k 2 = 3.1 s−1 for 1, k 2 = 12.8 s−1 for 2). [FeIVTPP]2C underwent one-electron ring oxidation to form a π-cation radical (k ox = 3.9 s−1) detected by UV–visible and IR spectroscopy. Imidazole-derivative formed a powerful oxidizing species that is able to oxidize the organic peroxide employed. The oxidant-intermediate reacting rapidly when produced in solution was proposed to be double-oxidized species due to its high reactivity (k red = 2660 M−1s−1). The results of UV–visible, IR, ESI-MS study supported the final products with Fe = C=Fe unit.