487002-09-5Relevant articles and documents
Catalytic Sulfoxidation and Epoxidation with a Mn(III) Triazacorrole: Evidence for A Third Oxidant in High-Valent Porphyrinoid Oxidations
Wang, Sheena Hailin,Mandimutsira, Beaven S.,Todd, Ryan,Ramdhanie, Bobby,Fox, Joseph P.,Goldberg, David P.
, p. 18 - 19 (2004)
The reaction between (TBP)8(Cz)Mn(III) (1) and the oxygen atom donors iodosylbenzene (PhIO) or p-cyanodimethylaniline-N-oxide (CDMANO) leads to the manganese(V)-oxo complex (TBP)8(Cz)Mn(V)≡O (2), which has been isolated and characterized previously. Under catalytic conditions with 1 as added catalyst and PhIO as oxidant, both sulfoxidation of PhSMe and epoxidation of cis-stilbene is observed, whereas with CDMANO no sulfoxidation takes place, suggesting that 2 is not the active oxidant. Examination of the independent reactivity of isolated 2 toward PhSMe and cis-stilbene supports this conclusion. A mechanism which relies on a novel type of oxidant involving Lewis acid activation of PhIO by the Mn(V)-oxo complex 2 accounts for these observations and is confirmed by 18O-labeling experiments. Copyright
A stable manganese(V)-oxo corrolazine complex
Mandimutsira, Beaven S.,Ramdhanie, Bobby,Todd, Ryan C.,Wang, Hailin,Zareba, Adelajda A.,Czernuszewicz, Roman S.,Goldberg, David P.
, p. 15170 - 15171 (2002)
The synthesis and characterization of an oxomanganese(V) corrolazine, (TBP) 8(Cz)Mn(V)O≡ (2), are reported. This remarkably stable high-valent complex is obtained from the stoichiometric reaction of (TBP) 8(Cz)Mn(III) (1) with m-CPBA and is easily purified by standard chromatographic methods on silica gel at room temperature. Complex 2 exhibits a diamagnetic 1H NMR spectrum indicative of a low-spin d 2 Mn(V)O≡ species. LDI-TOFMS of 2 shows the predicted isotopic envelope at m/z 1426.8. This envelope shifts to higher mass as expected after the facile exchange of the terminal oxo group with H218O. The resonance Raman spectrum of 2 either in solution or in the solid state shows a strongly enhanced Raman band for the stretching mode of the Mn-oxo bond, which also shifts as expected upon 18O substitution: 2(16O), 979 cm-1; 2(18O), 938 cm-1 (in CH2Cl2). Initial reactivity studies show that 2 rapidly transfers the terminal oxo ligand to PPh3, resulting in the quantitative formation of OPPh3 and concomitant reduction of 2 back to 1. Complex 2 is the first example of an oxomanganese(V)-porphyrinoid complex that can be isolated at room temperature. Copyright
A manganese(V)-oxo π-cation radical complex: Influence of one-electron oxidation on oxygen-atom transfer
Prokop, Katharine A.,Neu, Heather M.,De Visser, Sam P.,Goldberg, David P.
scheme or table, p. 15874 - 15877 (2011/11/13)
One-electron oxidation of MnV-oxo corrolazine 2 affords 2 +, the first example of a MnV(O) π-cation radical porphyrinoid complex, which was characterized by UV-vis, EPR, LDI-MS, and DFT methods. Access to 2 and 2+ allowed for a direct comparison of their reactivities in oxygen-atom transfer (OAT) reactions. Both complexes are capable of OAT to PPh3 and RSR substrates, and 2+ was found to be a more potent oxidant than 2. Analysis of rate constants and activation parameters, together with DFT calculations, points to a concerted OAT mechanism for 2+ and 2 and indicates that the greater electrophilicity of 2+ likely plays a dominant role in enhancing its reactivity. These results are relevant to comparisons between Compound I and Compound II in heme enzymes.
