Peroxo complexes oxidation

The two peroxo complexes possess remarkably similar reactivities toward most substrates (see Table IV). In all cases the peroxo complexes oxidize the substrate more rapidly than does H202 alone. 

A very recent example of carbene/palladium chemistry is reported by Stahl in which (NHC)2Pd add molecular oxygen to form a peroxo complex. Oxidative chemistry involving this type of complex as catalyst is expected to follow. This represents a fundamental departure of NHC ligands from phosphines due to their stability to oxidation Konnick MM, Guzei lA, Stahl SS (2004) J Am Chem Soc 126 10212... 

The [Co(DH)2L] complexes react with oxygen 137) to give j -peroxo complexes LCo(DH)2-02-Co(DH)2L, isolated using several ligands (not isocyanides however). These adducts are labile, and oxygen is easily lost. On standing these complexes can undergo oxidation, however, to /x-superoxo... 

In the same spirit DFT studies on peroxo-complexes in titanosilicalite-1 catalyst were performed [3]. This topic was selected since Ti-containing porous silicates exhibited excellent catalytic activities in the oxidation of various organic compounds in the presence of hydrogen peroxide under mild conditions. Catalytic reactions include epoxidation of alkenes, oxidation of alkanes, alcohols, amines, hydroxylation of aromatics, and ammoximation of ketones. The studies comprised detailed analysis of the activated adsorption of hydrogen peroxide with... 

Fe-Catalyzed Oxidation Reactions of Olefins, Alkanes, and Alcohols Involvement of Oxo- and Peroxo Complexes... 

Because there exist a number of reviews which deals with the structural and mechanistic aspects of high-valent iron-oxo and peroxo complexes [6,7], we focus in this report on the application and catalysis of iron complexes in selected important oxidation reactions. When appropriate we will discuss the involvement and characterization of Fe-oxo intermediates in these reactions. 

Keywords EXAFS H2O2 Hydroperoxo complexes IR Raman Partial oxidations Peroxo complexes TitanosUicate TS-1 UV-Vis XANES... 

Unfortunately, there is no Ti-hydroperoxo compound of known structure to be used as a model. Conversely, the structure of several Ti-peroxo complexes are known by diffraction studies [111-113], all of them showing the side on r] geometry. None of these compounds is known to be active in partial oxidation reactions [114,115]. Similar considerations can be addressed... 

Fig. 4. Substrate first binds to the complete system containing all three protein components. Addition of NADH next effects two-electron reduction of the hydroxylase from the oxidized Fe(III)Fe(III) to the fully reduced Fe(II)Fe(II) form, bypassing the inactive Fe(II)Fe(III) state. The fully reduced hydroxylase then reacts with dioxygen in a two-electron step to form the first known intermediate, a diiron(III) peroxo complex. The possibility that this species itself is sufficiently activated to carry out the hydroxylation reaction for some substrates cannot be ruled out. The peroxo intermediate is then converted to Q as shown in Fig. 3. Substrate reacts with Q, and product is released with concomitant formation of the diiron(III) form of the hydroxylase, which enters another cycle in the catalysis.

The aqueous solution chemistry of Tc(VII) is dominated by the stability of the TeO anion [4], Nitrido complexes are few and are limited to peroxides and one dimeric nitrido-hydrazido example. The peroxo complexes based on the [TcVIIN(02 )2] core are analogous to the well-known isoelectronic [MoviO(02)2] complexes [117] and are the only examples of nitridoperoxo complexes and rare examples of peroxo complexes of a metal in the +7 oxidation state. 

It seems very probable that the epoxidation reaction proceeds through a two-stage mechanism. Hydroperoxide oxidizes the catalyst to peroxo complex and the this complex performs epoxidation of olefins. 

Some evidence to suggest that peroxo complexes can be intermediates in the oxidation of Pt(II) by 02 has been presented. As shown in Scheme 41, a Pt(IV) peroxo complex was obtained by reacting cis-PtCl2(DMSO)2 and 1,4,7-triazacyclononane (tacn) in ethanol in the presence of air (200). An alkylperoxoplatinum(IV) complex is obtained in the reaction of (phen)PtMe2 (phen = 1,10-phenanthroline) with dioxygen and isopropyl-iodide. Under conditions that favor radical formation (light or radical initiators), an isopropylperoxoplatinum(IV) compound was obtained (201,202), depicted in Scheme 42. 

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