High valent copper

At least two reasonable mechanisms for copper-catalyzed aziridination using PhI=NTs can be postulated (Fig. 3). In one, copper is a redox catalyst and aziridination proceeds through a discrete, high-valent copper-imido intermediate (mechanism a). Alternatively, the copper catalyst may serve only as a Lewis acid... 

In the case of copper complexes, the chemistry is less well understood. High valent copper-oxo species are not likely to be formed, consequently copper-hydroperoxo or copper-hydroxo species are usually proposed as active species in DNA oxidation. These species are thus more susceptible to homo-lytic cleavage of the peroxide or the metal-hydroxo bond and consequently, to 1-electron oxidation mechanism. However, the labeling of the product of deoxyribose oxidation at Cl by Cu(l,10-phenanthroline)2 clearly demonstrated that these complexes can mediate a 2-electron oxidation mechanism of DNA damage since the oxygen atom incorporated in DNA originates from H2O. 

The copper complex of the diaminodiol (98) functions as a model foT galactose oxidase.A related diamidodiol (99) has been reported binding to high-valent Os and Ru, as well as in mixed [Cu L M(bipy)2] (M = Co, Ni, Zn) compounds, some of the latter being antiferromagnetically coupled. A number of diamine-diacid ligands have appeared, such as (100), ... 

Ghosh A, Wondimagegn T, Parusel ABJ (2000) Electronic structure of gallium, copper, and nickel complexes of corrole high-valent transition metal centers versus non-innocent ligands. J Am Chem Soc 122 5100-5104... 

Wasbotten IH, Wondimagegn T, Ghosh A (2002) Electronic absorption, resonance raman, and electrochemical studies of planar and saddled copper(III) mesw-triarylcorroles highly substituent-sensitive soret bands as a distinctive feature of high-valent transition-metal corroles. J Am Chem Soc 124 8104-8116... 

A highly reactive zero-valent copper species has been prepared by direct reduction of lithium 2-thienylcyanocuprate in THF with lithium naphthalenide <89SC1833>. 

O2 activation is a key step in enzymatic oxidation catalysis. Interaction with metals like copper or iron generates high valent metal species with high oxidizing power. Some bioinspired systems can carry out such an activation to yield reactive intermediates. Nevertheless, these can also be formed by shunt pathways using other chemical oxidizing compounds, and such examples will also be presented in this section. 

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