Catalytic oxidations using ruthenium porphyrins - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 15

olefins, alkanes, alcohols, phenols and amines (see Section 3), via reaction
pathways that illustrate the whole gamut of reactivity patterns”:
oxygenase, oxidase, and free-radical activity, see Section 1. More details
illustrating the importance of the disproportionation step (eq. 16) in the
catalytic oxygenations are given later (especially in Section 3.3).
Single oxygen atom donors, such as iodosylbenzene, m-
chloroperbenzoic acid ( m -CPBA), and amine oxides, have also
been reacted with Ru-porphyrins. In terms of mimicking the Fe(III) resting
state of cyto P-450 (Fig. 3), a Ru(III) precursor is an obvious candidate;
for example, reacts with PhIO according to the
stoichiometry of eq. 17 to yield a green complex, isolable at room
temperature and tentatively formulated as the oxo-Ru(IV) cation radical
species, ( 11 ) 8,69 ; an EPR signal at g = 2.00, the visible spectrum, and the

demonstrated stoichiometry of eq. 18, supported the formulation of ( 11 ) 70 ,
which showed some catalytic oxidation activity 8,69 (Section 3.3). The Ru(III)
precursors Ru(OEP)X (X = Cl, Br), synthesized from the corresponding
dihalo-Ru(IV) complexes 49,62 according to the chemistry outlined in eq. 19 71 ,
react with PhIO or m -CPBA again to generate a green solution, but work-up

procedures yield only species such as ( 12 ) 71 . Of note, corresponding
Fe(IV)-oxoporphyrin cation-radical species are also green 72,73 .
Addition of a 2-fold excess of

-CPBA, PhIO or to
or benzene solutions of the sterically hindered Ru(porp)CO complexes (porp
= TMP or TDCPP, Figure 4, cf. eq. 10) gives the
species, which are well characterized 15,40,61,64,74 , including a crystal structure
of the

m

complex 40 . The trans- dioxo complexes TDCPP are sensitive to

decomposition by traces of acids 64 (see Section 3.4).

Corresponding

oxidation of the non-hindered Ru(TTP)CO
with

-CPBA gave the species where L = OH or m-
chlorobenzoate 64 ; similarly, Ru(OEP)CO with gives a
product 75 . The derivatives with the non-hindered TPP and OEP
can be made by reaction of the appropriate Ru(porp)CO with

m

m -CPBA in

alcohol, the formation of species being inhibited by coordination of