Catalytic oxidations using ruthenium porphyrins - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 16

alcohol at the vacant site of the initially formed Ru(IV)(porp)O; the non-
hindered dioxo complexes are reasonably stable in the solid state and in
organic solvents, although they react readily with to form

Useful precursors for a myriad of derivatives are the 'bare” species
Ru(TMP) 59,76 , and the dimeric and species 58 . For
example, Ru(TMP), a 14-electron species, reacts readily with donor ligands
ranging from (which gives CO, olefins,
acetylenes, MeCN and ethers 59,76,77 . Figure 5 summarizes synthetic routes to
the trans- dioxo species using or an O-atom donor 59-61,67 .

3. OXIDATION OF ORGANIC SUBSTRATES

3.1 Oxidation of phosphines, phosphites, arsines and

stibines

of can be catalyzed by Ru(II) non-hindered
porphyrin species 57 . The mechanism in benzene solution involves an initial
outer-sphere oxidation of a 6-coordinate bis(phosphine) species which
generates superoxide according to eq. 12 (porp = OEP; ). Although
readily reduces species, the presence of protons
(needed as a cocatalyst) forces the equilibrium of eq. 12 to the right via
stabilization and subsequent disproportionation of to and (eq.

20). The oxidizes free while is regenerated using