Functional model oxygenations by nonheme iron complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 181

Rieske dioxygenases catalyse enantioselective cis-dihydrokylation of arene
and alkene double bonds (eq 8) and utilize a mono-nuclear nonheme iron active site.

Some nonheme monoiron complexes were found to catalyse the cis-
dihydroxylation with These catalysts are complexes of tetradentate N4
ligands such as TPA and BPMEN and capable of both epoxidation of olefins and
cis -dihydroxylation. Recently Ryu et al. found that
produces predominantly the cis -diol product with a diol : epoxide
ratio of 3-4 under conditions of limiting

186-191

as shown in Table 1.. 190 This is

contrast to the preferential epoxide formation with
It is reported that complexes forming low-spin Fe-OOH afford diols predominantly,
while those forming hi-spin Fe-OOH afford epoxides ( vide infra ).

4. FUNCTIONAL MODEL SYSTEMS FOR NONHEME IRON
MONOOXYGENASES
Monooxygenases catalyze the incorporation of one atom of oxygen from
molecular oxygen into substrates as shown in eq. 9.

Oxygenations proceed at nonheme mono- and diiron centers in the presence
of electron and proton donors that are important for activation of molecular oxygen.
The presence of the efficient electron and proton donor systems is characteristic of
the enzymatic systems. The most popular nonheme iron monooxygenase is soluble