Dioxygen reactivity

Using a new tripodal ligand, Sorrell and co-workers synthesized compound (61).83 The dioxygen reactivity of the pseudotetrahedral complex of this ligand of composition [(L)Cu(MeCN)][BF4] (not structurally characterized) was examined. In MeOH at —78 °C, the thermal decomposition of the side-on peroxodicopper(II) adduct in the presence of water yields a bis(hydroxide)-bridged... 

Keywords Biomimetic dioxygen reactivity Copper Coupling reactions ... 

Zhang C. X. Kaderli S. Costas M. KimE. -I. Neuhold Y. -M. Karlin K. D. Zuberbuhler A. D. Copper(I)-dioxygen reactivity of [(L)Cu(I)]( +) (L = tris(2-pyridylmethyl)amine) kinetic/thermodynamic and spectroscopic studies concerning the formation of Cu-02 and Cu2 02 adducts as a function of solvent medium and 4-pyridyl ligand substituent variations. Inorg. Chem. 2003, 42, 1807-1824. 

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.

Figure 8 Formation of an initial superoxo species has been long suspected in the formation of Cuj -peroxo species. For example the formation of (3) from [Cu (Nn)] proceeds with a very low (and sometimes negative) activation enthalpy, suggestive of the formation of an initial species Cu -Op - Cu (a). Direct observation of such an intermediate came from dioxygen reactivity studies with [Cu (TMPA)] complexes (b)...

Many CO2 insertion reactions to the metal-anion ligand bonds are known [2]. However most of the complexes having such reactivity are dioxygen reactive, therefore they can not be the appropriate means for atmospheric CO2 fixation. Here we will describe the atmospheric CO2 fixation by using Ni(II) complex. Some reports have presented the reaction of the metal-hydroxy complex with CO2 affording metal carbonato or bicarbonato complex as shown in scheme 1 [3]. 

In summary, the Coll(bpy)2 /HOOH/(4 1 MeCN/py) system forms a reactive intermediate (20) that selectively ketonizes methylenic carbon, and as such is closely similar to the intermediate of the Fe KPA)2/HOOH/(2 1 py/HOAc) system.36 The ability of FeP(DPAH)2 to activate O2 to an intermediate that has the same unique selectivity for hydrocarbon ketonization is further support for a common stabilized-dioxygen reactive complex (see Chapter 6), Several cobalt-dioxygen complexes exhibit oxygenase reactivity with organic substrates, 0,4l which is consistent with the dioxygen formulation for species 20. 

Kadish KM, Fremond L, Ou Z, Shao J, Shi C, Anson FC, Burdet F, Gros CP, Barbe JM, Guilard R (2005) Cobalt(III) corroles as electrocatalysts for the reduction of dioxygen reactivity of a monocorrole, biscorroles, and porphyrin—corrole dyads. J Am Chem Soc 127 5625-5631... 

Figure 7 Heme-Cu dioxygen reactivity in a model system from Karlin and co-workers.

C. Tetradentate vs. tridentate ligand influences in dioxygen reactivity 145... 

D. Summary of ligand effects on copper-dioxygen reactivity 161... 

In the past two decades, our understanding of the fundamentals of copper-dioxygen reactivity has flourished through coordination chemistry efforts... 

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... 

C. Tetradentate vs. Tridentate Ligand Influences in Dioxygen Reactivity... 

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]

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