Copper-dioxygen compound

In an elegant approach, Comba and co-workers initiated molecular-mechanics-based models that allow the rational design of ligand systems which are able to stabilize copper-dioxygen compounds. As a part of this investigation, complexes (241) (r = 0.12),223 (242) (r = 0.31),224 and (243) (r = 0.85)224 were synthesized and the reactivity of copper(I) complexes (Section 6.6.4.2.2(iv)) with dioxygen was investigated. 

Copper-dioxygen compounds or interactions of higher nuclearity exist in the multicopper oxidases (Cu 02 = 3 l) such as in ascorbate oxidase (AO), laccase, and ceruloplasmin, all of which couple the four electron reduction of O2 to water with the oxidation of a substrate (7). A number of AO protein X-ray studies are available, including a derivative with an end-on... 

Two structural types of tetranuclear copper-dioxygen compounds exist where the peroxide is bridged by four Cu(II) ions in either a cis (56,57) or trans (58) environment (Fig. 5). However, the mechanism of formation of these species from Cu /02 chemistry is not well understood considering that reduction to peroxide only requires two electron equivalents yet the compound provides 4 electrons from Cu(I). 

Continuing their efforts with similar ligands, they prepared a thermally sensitive crystal of a bis(/i-qxo)dicopper(II I) compound (3).28 Average Cu O bond distance and Cu-Cu distance are 1.806 A and 2.743 A, respectively. Spectroscopic and kinetic parameters for this compound were also investigated. They also studied the reactivity properties of the copper-dioxygen complexes.25... 

Metal ions play an important role in several of these oxidative reactions as well as in biological dioxygen metabolism. As an example, copper(II) acetate and hydrogen peroxide have been used to produce a stable oxidizing agent, hydroperoxy copper(II) compound. The same oxidation system is also obtained from copper(II) nitrate and hydrogen peroxide (Eq. 1) [103] but requires the neutralization of ensuing nitric acid by potassium bicarbonate to maintain a pH 5. 

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... 

The oxidation of alcohols in a basic solution catalyzed by Cu(II) o-phenanthroline complexes has been recently studied by Sakharov and Skibida [305-309], The copper-phe-nanthroline complex is stable in a basic solution and appears to be a very efficient catalyst for the oxidation of alcohols to carbonyl compounds. The reaction rate increases with an increase in the partial pressure of dioxygen. The solvent dramatically influences the reaction rate (conditions 348 K, [MeOH] = 20%vol, [Cu—(o—phm)] = 0.01 mol L-1). 

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