W. Nam et al., Participation of two distinct hydroxylating intermediates in iron(III) porphyrin complex-catalyzed hydroxylation of alkanes, J AM CHEM S, 122(44), 2000, pp. 10805-10809
We have obtained evidence that acylperoxo-iron(III) porphyrin complexes la
are involved as reactive hydroxylating intermediates in the hydroxylation o
f alkanes by m-chloroperoxybenzoic acid (m-CPBA) catalyzed by electron-defi
cient iron(III) porphyrin complexes containing chloride as an anionic axial
ligand in a solvent mixture of CH2Cl2 and CH3CN at -40 degreesC. In additi
on to the intermediacy of la, oxoiron(IV) porphyrin cation radical complexe
s 2 are formed as the reactive hydroxylating intermediates in the alkane hy
droxylations by m-CPBA catalyzed by the iron(III) porphyrin complexes conta
ining triflate (CF3SO3-) as an anionic axial ligand under the same reaction
conditions. In line with the recent proposal by Newcomb, Goon, Vat, and co
-workers for cytochrome P-450 reactions, these results suggest that two dis
tinct electrophilic oxidants such as la and 2 effect the alkane hydroxylati
ons in iron porphyrin models, depending on the reaction conditions such as
the nature of the anionic axial ligands of iron(III) porphyrin complexes.