Synthesis, Characterization, and Reactivities of Manganese(V)−Oxo Porphyrin Complexes

Abstract

The reactions of manganese(III) porphyrin complexes with terminal oxidants, such as mchloroperbenzoic acid, iodosylarenes, and H 2 O 2 , produced high-valent manganese(V)-oxo porphyrins in the presence of base in organic solvents at room temperature. The manganese(V)-oxo porphyrins have been characterized with various spectroscopic techniques, including UV-vis, EPR, 1 H and 19 F NMR, resonance Raman, and X-ray absorption spectroscopy. The combined spectroscopic results indicate that the manganese(V)-oxo porphyrins are diamagnetic low-spin (S = 0) species with a longer, weaker Mn-O bond than in previously reported Mn(V)-oxo complexes of non-porphyrin ligands. This is indicative of double bond character between the manganese(V) ion and the oxygen atom, and may be attributed to the presence of a trans-axial ligand. The Figure S2), UV-vis spectrum of (TM-2-PyP)Mn V =O ( Figure S3), UV-vis and EPR spectra of (TDCPP)Mn IV =O (2a) (Figure S4), time traces for the natural decay of 1a in the presence of different amounts of base ( Figure S5), and LC-ESI MS of PPh 3 O obtained in isotope labeling experiment ( Figure S6). NIH Public Access

Spectroscopic observation of iodosylarene metalloporphyrin adducts and manganese(V)-oxo porphyrin species in a cytochrome P450 analogue

“…2g). The great change of the l max (from 477 to 430 nm) indicated the change of the oxidation state of metal and known synthetic high-valent manganese-oxo porphyrins have l max in the range of 420 to 450 nm 6,10 . In addition, Newcomb et al 12 54 .…”

“…It exhibits promising catalytic behaviour for a host of oxidative reactions, and so a primary goal of cytochrome P450 research is in the application of these enzymes, or their derivatives, in catalytic oxidation of unactivated C-H bonds, such as the hydroxylation of cyclohexane. Many synthetic metalloporphyrin model compounds have been synthesized to probe the mechanisms of the behaviours of cytochrome P450 oxygenases [3][4][5][6][7][8][9][10][11][12][13] , but the detailed pathways are still elusive, especially for the steps involving highly reactive intermediates. For a long time, it has been believed that oxoiron (IV) porphyrin p-cation radical (named as Compound I) is the unique reactive intermediate in cytochrome P450 catalysed oxidative reactions (Fig.…”

Detection of different oxidation states of individual manganese porphyrins during their reaction with oxygen at a solid/liquid interface

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[4][5][6][7] . The majority of these studies use ensemble techniques in solution, such as electrochemistry and absorption, electron paramagnetic resonance and nuclear magnetic resonance spectroscopy.

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Biomimetic Epoxidation of Olefins Catalyzed by Metalloporphyrins with Molecular Oxygen

“…The changes of UV-vis spectra are indicative of the existence of an active species expected as the high-valent iron porphyrin. [96][97][98] It is usually considered that μ-oxo dimeric metalloporphyrins could easily form monometalloporphyrins during the catalytic process. In fact, whether the dinuclear intermediate or the mononuclear intermediate is the active species remain controversial for the oxygenation of hydrocarbons catalyzed by μ-oxo dimeric metalloporphyrins.…”