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Adding HClO4 to [(BnTPEN)MnIII–OO]+ in MeOH generates a short-lived MnIII–OOH species, which converts to a putative MnV＝O species. The potent MnV＝O species in MeCN oxidizes the pendant phenyl ring of the ligand in an intramolecular fashion. The addition of benzene causes the formation of (BnTPEN)MnIII-phenolate. These findings suggest that high valent Mn species have the potential to catalyze challenging aromatic hydroxylation reactions. [ABSTRACT FROM AUTHOR]

An efficient electrochemical method for the selective oxidation of alcohols to their corresponding aldehydes/ketones using a biomimetic iron complex, [(bTAML)FeIII–OH2]−, as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes using water as an oxygen source is reported. The substrate scope also includes alcohols that contain O and N heteroatoms in the scaffold, which are well tolerated under these reaction conditions. Mechanistic studies show the involvement of a high-valent FeV(O) species, [(bTAML)FeV(O)]−, formed via PCET (overall 2H+/2e−) from [(bTAML)FeIII–OH2]− at 0.77 V (vs. Fc+/Fc). Moreover, electrokinetic studies of the oxidation of C–H bonds indicate a second-order reaction, with the C–H abstraction by FeV(O) being the rate-determining step. The overall mechanism, studied using linear free energy relationships and radical clocks, indicates a "net hydride" transfer, leading to the oxidation of the alcohol to the corresponding aldehyde or ketone. When the reaction was carried out at pH > 11, the reaction could be carried out at a ∼500 mV lower potential than that at pH 8, albeit with reduced reaction rates. The reactive intermediate involved at pH > 11 is the corresponding one-electron oxidized [(bTAML)FeIV(O)]2− species. [ABSTRACT FROM AUTHOR]

Selective catalytic oxygenation of unactivated C–H bonds for a series of substrates by dioxygen using iron complexes was performed without the use of a co-reductant. Mechanistic studies indicate that the reaction proceeded via the autocatalytic formation of an oxoiron(V) intermediate, which brings high regioselectivity and stereoretention. [ABSTRACT FROM AUTHOR]

Adding HClO 4 to [(BnTPEN)Mn III -OO] + in MeOH generates a short-lived Mn III -OOH species, which converts to a putative Mn V O species. The potent Mn V O species in MeCN oxidizes the pendant phenyl ring of the ligand in an intramolecular fashion. The addition of benzene causes the formation of (BnTPEN)Mn III -phenolate. These findings suggest that high valent Mn species have the potential to catalyze challenging aromatic hydroxylation reactions.

An efficient electrochemical method for the selective oxidation of C-H bonds of unactivated alkanes (BDE ≤97 kcal mol -1 ) and C[double bond, length as m-dash]C bonds of alkenes using a biomimetic iron complex, [(bTAML)Fe III -OH 2 ] - , as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes is reported. The O-atom of water remains the source of O-incorporation in the product formed after oxidation. The products formed upon oxidation of C-H bonds display very high regioselectivity (75 : 1, 3° : 2° for adamantane) and stereo-retention (RC ∼99% for cyclohexane derivatives). The substrate scope includes natural products such as cedryl acetate and ambroxide. For alkenes, epoxides were obtained as the sole product. Mechanistic studies show the involvement of a high-valent oxoiron(v) species, [(bTAML)Fe V (O)] - formed via PCET (overall 2H + /2e - ) from [(bTAML)Fe III -OH 2 ] - in CPE at 0.80 V ( vs. Ag/AgNO 3 ). Moreover, electrokinetic studies for the oxidation of C-H bonds indicate a second-order reaction with the C-H abstraction by oxoiron(v) being the rate-determining step., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)