Copper peroxo complexes

As a part of their ongoing investigations into the reaction of dioxygen with copper(I) complexes to identify copper-superoxo/peroxo intermediate species, Schindler and co-workers51-53 have also provided examples of a number of mononuclear copper(II) complexes (Table 1) (as well as copper(I) Section 6.6.4.2.1). 

Figure 5.20 Square-pyramidal copper(II) peroxo complex exhibiting reversible oxygena-tion/deoxygenation behavior. (Adapted from references 47 and 41a.)...

At present, we do not completely understand why only some of these very similar m-xylyl dicopper(I) complexes systems described above undergo ligand oxygenation reactions. However, based on the results outlined above, we can speculate on a number of aspects of this 02-activation process. Our studies implicate the presence of a copper-dioxygen (peroxo dicopper(II)) adduct as an intermediate in the oxygenation reaction and more recent kinetic studies (51) further support this conclusion. This adduct then either directly or via some further intermediate undergoes an electrophilic attack of the arene. The unique nature of this very fast reaction 2->3, and the observed inability to intercept the active... 

Oxygenic photosynthetic organisms, [2Fe-2S] ferredoxins, 38 224-233 Oxygenyl ion, preparation of, 9 229 Oxyhalides, of berkelium, 28 49, 51-53 Oxyhalogeno cations, 9 276-279 Oxyhemerythrin, 40 373-374, 45 84 XAS, 36 325 Oxyhemocyanin, 40 363 m-peroxo dinuclear copper complexes as models for, 39 41-52 physicochemical properties, 39 47-48 Oxyhemocyanins, XAS, 36 326-327 Oxyhemoglobin, 21 135 Oxyiodonium cations, 9 277 Oxymanganese phthalocyanine, strucmre of, 7 31-35... 

Several other peroxo bridged complexes have been lately synthesized53-54 simply by reacting appropriate precursors and dioxygen, as shown in equation 7 for di-Ir(II) complex 5, with bis(diphenylphosphinomethane) dppm, and in equation 8 for a dicopper(II) species 6. The same procedure has been also applied to obtain a peroxo bridged heme-copper complex 755 (equation 9). 

A side-on p,-Tq2 Tq2-peroxo dicopper(II) complex. A very important development in copper-dioxygen chemistry occurred in 1989 with the report by Kitajima et al. [10,108] that another Cu202 species could be prepared and structurally characterized by using copper complexes with a substituted anionic tris(pyrazolyl)borate ligand. This intensely purple compound, Cu[HB(3,5-iPr2pz)3] 2(02) (5), was prepared either by reaction of Cu[HB(3,5-iPr2pz)3] (4) with 02 or by careful addition of aqueous hydrogen peroxide to the p-dihydroxo... 

A. ix-Peroxo Dinuclear Copper Complexes as Models for Oxyhemocyanin and... 

B. Reaction Aspects of p,-Peroxo Dinuclear Copper Complexes Relevant to Tyrosinase Catalysis... 

Figure 4 Aliphatically tethered Cu -peroxo complexes (a) and (b). Figure 4(c) depicts the distortion, or butterflying, of the Cu202 core facilitated by the ligand constraints the aliphatic tether imposes on the copper complex. Figure 4(d) depicts the structure of oxyHc from Limulus polyphemus, which shows some degree of butterflying of the Cu202 core...

Recently, however, examples of the long-sought stable binuclear copper(II) peroxo complex have been successfully synthesized and characterized, and interestingly enough, two entirely different structural types have been identified, i.e., /u,-l,2 and dioxygen complexes(see 5.47)... 

Copper complexes of amines such as histidine,42 ethylenediamine and 2,2 -bipyridine have been studied as models for the behavior of copper enzymes which catalyze the decomposition of H202 to 02 and H20 peroxo species are believed to be intermediates.428... 

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