Copper complex binuclear

The reaction of binuclear copper complexes with oxygen as models for tyrosinase activity was also markedly accelerated by applying pressure (106408 ). Tyrosinase is a dinuclear copper protein which catalyses the hydroxylation of phenols. This reaction was first successfully modeled by Karlin and co-workers (109), who found that an intramolecular hydroxylation occurred when the binuclear Cu(I) complex of XYL-H was treated with oxygen (Scheme 5). 

The basic study was performed on copper complexes with N,N,N, N1-tetramethylethane-1,2-diamine (TMED), which were known to be very effective oxidative coupling catalysts (7,12). From our first kinetic studies it appeared that binuclear copper complexes are the active species as in some copper-containing enzymes. By applying the very strongly chelating TMED we were able to isolate crystals of the catalyst and to determine its structure by X-ray diffraction (13). Figure 1 shows this structure for the TMED complex of basic copper chloride Cu(0H)Cl prepared from CuCl by oxidation in moist pyridine. 

The same complex could be obtained starting from CuC and subsequent substitution of both bridged chlorides by adding hydroxyl ions. Scheme 3 describes the formation and interconversion of both binuclear copper complexes. 

The other copper-only binuclear centre to be considered is the CuA or purple copper complex. It is part of the terminal oxidase in mitochondrial respiration, cytochrome c oxidase (COX). Its EPR signature, a seven-line spectrum, has since long been known to be different from the classes type 1 to 3 and arises from two copper ions in a 1.5 valence (or mixed valence) state, first proposed from EPR-analysis of a similar center in nitrous oxide (N20) reductase. There is a close correspondence between the blue and purple states of copper since each of the two copper ions in CuA can be considered as being structurally related to the mononuclear blue site coordination. 

Maverick. A.W. and Klavetter, F.E. (1984) Cofadal binuclear copper complexes of a bis(P-diketone) ligand. Inorg. Chem., 23, 4129 130. 

Sulfur ligands, 633-655 coordination ability, 516 Sulfur monoxide metal complexes instability, 636 Superoxide dismutase, 773 copper complexes, 772 Superoxo complexes, 315-330 binuclear, 323, 325 reactions, 330 bridged... 

The reaction of imidazole-4,5-dicarbaldehyde with 2-aminoethylpyridine in the presence of copper(II) chloride has enabled the preparation of a binuclear complex (equation 2).29 A more common class of binuclear complex is based on template reactions of a phenolic dialdehyde with various amines and includes the copper complexes (14)30 31 and (15).32 Reactions of this type can be extended to the synthesis of macrocyclic binuclear complexes such as (16).33,34... 

Developing the study of binuclear copper complexes with NCS bridge fragments [48], the transformation (4.3) was carried out [49] ... 

Our own work in the area of aerobic oxidations was inspired by the exquisite research performed on the structure and reactivity of the binuclear copper proteins (7), hemocyanin and tyrosinase, and by the seminal contribution of Riviere and Jallabert (8). These two authors have shown that the simple copper complex CuCl - Phen (Phen = 1,10-phenanthroline) promoted the aerobic oxidation of benzylic alcohols to the corresponding aromatic aldehydes and ketones (Fig. 2). 

Figure 3 Binuclear copper complexes in octopus hemocyanin (a) and sweet potato catechol oxidase (b) showing the thioether linkage between a cysteine residue and a directly coordinating histidine imidazole. Heteroatoms (N,0,S) are indicated by a shaded quadrant. [ortep-III views based on PDB ID 1JS8 and IBTl]...

The reaction of dioxygen with laccase or ascorbate oxidase was reviewed in Section IX and in Messerschmidt et al. (74), where the possible binding modes of dioxygen to binuclear and trinuclear copper centers are discussed. A novel mode of dioxygen binding to a binuclear copper complex was found in a compound synthesized by Kitajima et al. (165). The complex contains peroxide in the mode, i.e., side-on between... 

There are many structural studies of copper coordination compounds with azide ligands, mainly of mononuclear and binuclear copper complexes but a few also of trinuclear copper complexes. A comprehensive... 

Many binuclear copper complexes have been synthesized as models for binuclear sites in... 

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