PEROXO-TRANSITION METAL COMPOUNDS

See related PEROXO- TRANSITION METAL COMPOUNDS, PEROXOCHROMIUM COMPOUNDS... 

AH of the commercial inorganic peroxo compounds except hydrogen peroxide are described herein, as are those commercial organic oxidation reactions that are beheved to proceed via inorganic peroxo intermediates. Ozonides and superoxides are also included, but not the dioxygen complexes of the transition metals. 

Mechanism of Olefin Epoxidation by Transition Metal Peroxo Compounds... 

During the last three decades, peroxo compounds of early transition metals (TMs) in their highest oxidation state, like TiIV, Vv, MoVI, WV1, and Revn, attracted much interest due to their activity in oxygen transfer processes which are important for many chemical and biological applications. Olefin epoxidation is of particular significance since epoxides are key starting compounds for a large variety of chemicals and polymers [1]. Yet, details of the mechanism of olefin epoxidation by TM peroxides are still under discussion. 

The olefin oxygenations carried out with dioxygen seem to be metal-centered processes, which thus require the coordination of both substrates to the metal. Consequently, complexes containing the framework M (peroxo)(olefin) represent key intermediates able to promote the desired C-0 bond formation, which is supposed to give 3-metalla -l,2-dioxolane compounds (Scheme 6) from a 1,3-dipolar cycloinsertion. This situation is quite different from that observed in similar reactions involving middle transition metals for which the direct interaction of the olefin and the oxygen coordinated to the metal, which is the concerted oxygen transfer mechanism proposed by Sharpless, seems to be a more reasonable pathway [64] without the need for prior olefin coordination. In principle, there are two ways to produce the M (peroxo)(olefin) species, shown in Scheme 6, both based on the easy switch between the M and M oxidation states for... 

It is somewhat surprising that Mn compounds with 02 moieties appear to have such limited existence peroxo compounds of the higher oxidation states are an important feature of the earlier transition metals (and we shall notice a few, poorly characterized, examples for Mn in Section 41.5.3) and the metals which follow manganese—Fe and Co—have an extensive and important chemistry of reversible combination with the oxygen molecule. It is perhaps pertinent to recall that some Mn11 species are very efficient catalysts for the decomposition of hydrogen peroxide (Section 41.3.3.7). 

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