ISSN:
1434-1948
Keywords:
Fluorinated porphyrins
;
Electrochemistry
;
Manganese
;
Oxidation catalysis
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis and characterization of manganese complexes of β-octafluoro-meso-tetraarylporphyrins are reported. The presence of the electron-withdrawing β-fluorine atoms induces a very large shift of the redox potential for the oxidation of the manganese(II) derivatives. With the meso-aryl group bearing two ortho-chlorine atoms (2,6-dichlorophenyl) or five fluorine atoms (pentafluorophenyl), metal complexation leads to the isolation of pure manganese(II) compounds. The stability and catalytic activity of these new derivatives have been studied using hydrogen peroxide and iodosylbenzene as oxidants, and standard substrates for epoxidation and hydroxylation reactions. The results are compared to those obtained with the β-hydrogenated analogs under the same conditions. In the case of hydrogen peroxide, the high level of porphyrin degradation prevents efficient catalytic activity. With iodosylbenzene as oxidant, both stability and epoxidation are similar to those of the β-hydrogenated porphyrins, however, a substantial improvement in the efficiency of the hydroxylation of cyclohexane is observed with up to 33 turnovers with (perfluorotetraphenylporphyrin)manganese(II).
Additional Material:
8 Tab.
Type of Medium:
Electronic Resource
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