Porphyrin manganese

Green-yellow salts of the tetrahedral [MX4] (X = Cl, Br, I) ions can be obtained from ethanolic solutions and are well characterized. Furthermore, a whole series of adducts [MnX2L2] (X = Cl, Br, I) are known where L is an N-, P- or A -donor ligand, and both octahedral and tetrahedral stereochemistries are found. Of interest because of the possible role of manganese porphyrins in photosynthesis is [Mn (phthalocyanine)] which is square planar. The reaction of aqueous edta with MnC03 yields... 

Table 6.6 Manganese/porphyrin-catalyzed epoxidation of cis-cy-dooctene with aqueous H2O2 (30%).

One example has used a manganese porphyrin and iodobenzene encapsulated within a dendrimer to bring about shape-selective epox-idation of alkenes. The important aspect of catalysts is that the reactants can move rapidly to the active site, and that the products can be removed rapidly from the active site and expelled from the dendrimer. 

Recently, Breslow19 reported a regioselective and stereoselective hydroxylation of steroid substrates catalyzed by manganese porphyrin... 

N. Diab and W. Schuhmann, Electropolymerized manganese porphyrin/polypyrrole films as catalytic surfaces for the oxidation of nitric oxide. Electrochim. Acta 47, 265-273 (2001). 

In company with manganese porphyrin complex, ruthenium porphyrins have already shown great catalytic activity in the intermolecular amidation of saturated G-H bonds. However, examples of amidation of aromatic... 

Figure 5.11 Entrapped in a silica aerogel, this manganese porphyrin is nine times more active than in solution. (Reproduced from ref. 22, with permission.)...

Tokuda, J. Ohura, R. Iwasaki, T. Takeuchi, Y. Kashiwada, A. Nango, M. Decoloration of azo dyes by hydrogen catalyzed by water-soluble manganese porphyrins. Textile Res. J. 1999, 69, 956-960. 

In the case of manganese porphyrin catalyzed epoxidations, the axial ligands have been used alone or together with other additives like carboxylic acids (Banfi and coworkers) and soluble bases (Johnstone and coworkers). For example, Mansny and coworkers showed that in the presence of imidazole, 2-methylimidazole or 4-imidazole chloromanganese(tetra-2,6-dichlorophenylporphyrin) catalyzes the epoxidation of varions aUtenes including 1-alkenes by Under these conditions alkene conversion... 

It has been observed that PI14PHSO5 alone does not transfer its oxygen to manganese porphyrin. It is necessary to add either imidazole or pyridine derivatives, i.e. species which act as axial ligands in metalloporphyrins and are known to accelerate also the catalytic oxidation of organic substances . The kinetics and mechanism of manganese porphyrins oxidation by PI14PHSO5 were well studied . ... 

Figure 1. PhIO oxidation of cyclooctene catalyzed by various sulfonated manganese porphyrin immobilized on methylated PVP, [Mn-porphyrin-S-PVPMe+][TsO-]. [MnTMPS-PVPMe+][TsO-] (O), [MnBrgTMPS-PVPMe+][TsO-] ( ), [MnTDCPPS-PVPMe+][TsO-] (1) and [MnCli2TMPS-PVPMe ][TsO ] (O). Conditions cyclooctene (150 imol), PhIO (750 jimol), Mn-porphyrin-S (2 jimol) immobilized on [PVPMe+][TsO-] (200 mg of PVP treated by TsOMe) in 3 mL of dichloromethane at room temperature. (Reproduced from ref. 12a. Copyright 1992 American Chemical Society.)...

Manganese porphyrins can be solubilized in aqueous solution by the attachment of charged functional groups to the porphyrin... 

Scheme 4 Electron- and proton-transfer reactions of manganese porphyrins in aqueous media.

I 76 Electrochemistry of the Croup 7 Elements Manganese, Technetium, and Rhenium Tab. 3 Electrochemical data for manganese porphyrins in aqueous media ... 

Fig. 8 Proposed mechanism of electrocatalytic epoxidation of olefins by manganese-porphyrin catalysts (reprinted with...

Recently, Sugimoto et al. demonstrated that manganese-porphyrin complex 39 co-polymerized GHO with G02- Even under 0.10 MPa of GO2, the co-polymerization proceeds to give a co-polymer with high carbonate linkage content of 95%. 

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