Dioxygen, reactivity with copper

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. 

Figure 18. Comparison of half-met hemocyanin with the half-met type 3 (in T2D) laccase copper sites. A EPR spectra and binding constants of exogenous azide binding. B Spectroscopically effective structural models for exogenous ligand binding to the half-met derivatives and their relation to differences in dioxygen reactivity.

Figure 21. Laccase copper centers required for dioxygen reactivity. A XAS of fully reduced T2D laccase and fully reduced T2D laccase following exposure to dioxygen. B XAS of reduced TIHg laccase and reduced TIHg laccase following exposure to dioxygen. C Summary of the reactivity of deoxy T2D, fully reduced T2D, and reduced TIHg laccase with oxygen.

Reactivity of copper(I) complexes with heterocyclic ligands towards dioxygen 00EJI2311. 

The ligand changes effect large variations in their dioxygen reactivity The reaction of [Cu(TMPA)(MeCN)] with O2 in propionitrile at low temperatures initially generates an unstable copper(II)-superoxo compound (A.max 410 nm, 4,000 M cm 747 nm s 1,000 M cm ) and then... 

Early copper(T)/dioxygen reactivity studies were done with the classic tripodal pyridyl-amine ligand TMPA (Fig. 8) (see above). The low-temperature reaction of [Cu(TMPA)(RCN)]PF6 (R = Me or Et) with O2 was found to produce a dicopper-dioxygen adduct where the peroxide is bound in a [Pg.145]

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... 

This centre consists of a pair of Cu11 ions, which are diamagnetic as a result of antiferromagnetic interaction. It is characterized by a strong absorption at around 330 nm with extinction coefficients in the range 3000 to 5000 dm3 moF1 cm-1. The type 3 centre is associated with redox reactions of dioxygen, as it can transfer two electrons and so bypass the formation of reactive superoxide. A number of model systems for type 3 copper have been reported. 

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