Functional model oxygenations by nonheme iron complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 184

proposed involves the initiation of the reaction by the homolytic reaction with C-H
bonds to form a carbon radical, followed by rapid trapping with to form the alkyl
hydroperoxide. Decomposition of the peroxide is catalyzed by the initial FeOFe
complex to form alcohol, aldehyde or ketone. A complex with an aqua ligand in
place of the acetate ligand was synthesized and used for the alkane functionalization
reaction. 204 Compared with the complex, the complex resulted in the

higher turnovers/h (approximately twice) (Table 2).

It was suggested that the loss of the terminal or ligand by TBHP
displacement must be rate limiting in the formation of the active Fe oxidant
complex. The radical clock experiment using trans -2-phenylmethycyclopropane
indicated that the radical rearrangement of the cyclopropylcarbinyl to phenyl-but-3-
enyl radical is faster than trapping. This conflicts with the no ring-opened
product formation by MMO, suggesting the nonradical formation in the MMO-
catalyzed C-H functionalization reaction. 205 The free radical process in the MMO
alkane functionalization is also suggested by the formation of the partially
racemized products from optically active ( S ) - or ethanes. 206
Studies on the complex with the aqua ligand were extended to the reaction in
aqueous solutions. 207, 208 Complexes, (L = TPA or
BPIA) and were prepared in situ using
and used to the reaction of soluble substrates, i.e., alcohols, at pH 4.2 in
the presence of It was shown that the complexes catalyze the homolytic
decomposition of TBHP and the generated and radicals initiate
homolytic C-H bond abstraction from the alcohol substrate to predominantly provide
the aldehyde/ketone product.
Reactivity of dinuclear iron complexes with simple bidentate ligands such as
2,2'-bipyridine and 1,10-phenanthroline for oxidation of alkanes, toluene, dimethyl
sulfide, trans -stilbene and adamantane was studied in under Ar in the
presence of oxidants (TBHP, CHP or ). The effect of the number of the
bridging ligand was found remarkable: monobridged >