Hydroperoxo chromium

M(IV)-peptide radicals, and decay to final products have been determined (96). Interestingly, the rate constants for both the formation and decay of the high-valent intermediate are much larger than the corresponding values in the chromium system in Scheme 1. Thus the lifetimes of both the hydroperoxo species and M(IV)-peptide radicals are much shorter in the enzymatic system than for the chromium macrocycles. 

Electrophilic activation of coordinated peroxides can be achieved by protonation, which typically yields end-on coordinated hydroperoxides.16 For example, the well-defined hydroperoxo complexes of rhodium and chromium efficiently oxidize inorganic substrates such as halide anions these reactions are acid catalyzed.16 Hydroperoxo intermediates were implicated in some enzymatic oxidations, such as hydroxylation catalyzed by cytochrome P450 (Figure 4.32). Although significant... 

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