Remarkable axial thiolate ligand effect on the oxidation of hydrocarbons by active intermediate of iron porphyrin and cytochrome P450

In order to examine the reactivity of active intermediate derived form iron porphyrins, competitive oxidations of alkane and alkene were carried out. It has been proposed that the first step of alkane hydroxylation is Il atom abstraction and that of alkene is one-electron transfer. Therefore, it is expected that alkene-alkane competitive oxidation can be used as a probe fo r discrimination of differences in chemical properties among active species . Cytochrome P450 and SR complex, which is a stable thiolate-ligated iron p orphyrin, mediated the oxidation of alkane much more preferentially than ir on porphyrin coordinated by imidazole or chloride. These results indicate t hat thiolate coordination alters the reactivity of the two-electron-oxidize intermediate in a manner that is much more favorable to alkane hydroxylati on than the case of chloride or imidazole coordination. (C) 2000 Elsevier S cience B.V. All rights reserved.