On copper complex

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. 

Physical Measurements on Copper Complexes.—Detailed discussion of papers concerned purely with spectroscopic and magnetic data obtained for copper complexes is now covered by the Chemical Society Specialist Periodical Report Electronic Structure and Magnetism of Inorganic Compounds (ed. P. Day), Volumes 1 and 2, and will not be included here. However, three papers of some significance are cited below and other papers on this subject listed in Table 5. 

The assembly of solar cells based on copper complexes required 2 optimization and multilayered photoanodes with a compact 2 underlayer, necessary to suppress the back recombination from the exposed FTO contact. The photoelectrochemical characterization carried out with a 0.2 M Cu(I)/Cu(II) electrolyte (Cu(II) molar... 

Coloured copper complexes with EDTA and related reagents can be applied for determining Cu at higher concentrations. Cu has been determined as EDTA and NTA complexes by the derivative spectrophotometry [84,85]. Relatively high concentrations of Cu can be determined as the ammino complex (e = 120). Other sensitive methods are based on copper complexes with chloride (in water-acetone) and azide [86]. 

The studies on copper complexes demonstrated that the phanephos ligand (see Fig. 2) can be successfully applied to engineer highly luminescent Cu(i) complexes. The rigid [Cu(dmp)(phanephos)] complex displays a high luminescence quantum yield of 0.8 at ambient temperature. In contrast to the long-lived phosphorescence of 240 ps at low temperature, the ambient-temperature emission represents a thermally activated delayed fluorescence with a decay time of 14 ps. ... 

The above method, contrary to the methods of estimation of amino acids based on copper complexes, is selective. A threefold excess of several common amino acids (including histamine) does not interfere. The method thus enables free histidine to be determined in protein hydrolysates, provided that the histidine concentration is sufficiently high. Tryptophane deforms the polaro-graphic waves when present in an amount corresponding to half that of histidine (above 1 mg/10 ml.). Mercaptoamino acids also interfere, but most of the types of compounds are destroyed during the protein acidic hydrolysis. Glycine affects the end-point if present in amounts larger than 10 mg/10 ml. of the sample. 

In the beginning, we have focused on copper complexes that catalyze the hydrolysis of carboxylic esters, and at a later stage of the project, oxidation reactions by O2 or H2O2. Figure 3.4 summarizes the newly synthesized fluorophore-labeled chelators, and their properties are briefly discussed below. A significant advantage of the DNA-linked chelators is that they can be readily combined with both a reporter fluorophore and a functionality for surface immobilization by hybridization with a complementary DNA strand that is 3 terminally functionalized with, for example, tetramethylrhodamine (TMR) and 5 -functionalized with biotin for interaction with surface-bound streptavidin. 

This interpretation is supported by literature studies on copper(II) complexes containing two -amino-acid ligands. For N-unsubstituted -amino-acid ligands, deductions as to position of the cis -trans geometrical equilibrium in solution are difficult as illustrated by the fact that for some -amino acids solid complexes have been isolated of both the ds and trans geometry. In contrast it seems as if copper(II) complexes containing two N-alkylated -amino-acid ligands crystallise exclusively in the trans form ". ... 

Piperazinothiazoies (2) were obtained by such a replacement reaction, Cu powder being used as catalyst (25. 26). 2-Piperidinothiazoles are obtained in a similar way (Scheme 2) (27). This catalytic reaction has been postulated in the case of benzene derivatives as a nucleophilic substitution on the copper-complexed halide in which the halogen possesses a positive character by coordination (29). For heterocyclic compounds the coordination probably occurs on the ring nitrogen. 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

The most widely reported developments have been in category 4, ie, 4,4 -dinitro-2,2 -stilbenedisulfonic acid (1) condensations with amino-containing azo components, some of which ate copper complexes, to give dyes having excellent properties on leather (19—31) (Table 2). 

Of all the metal complexes evaluated, copper phthalocyanines give the best combination of color and properties and consequentiy the majority of phthalocyanine dyes are based on copper phthalocyanine Cl Direct Blue 86 [1330-38-7] (Cl 74180) (68) is a typical dye. 

Available information on the mechanism of cyclocondensation is rather contradictory. According to one hypothesis, both the condensation of aryl halides with copper acetylides and the cyclization occur in the same copper complex (63JOC2163 63JOC3313). An alternative two-stage reaction route has also been considered condensation followed by cyclization (66JOC4071 69JA6464). However, there is no clear evidence for this assumption in the literature and information on the reaction of acetylenyl-substituted acids in conditions of acetylide synthesis is absent. 

Since Evans s initial report, several chiral Lewis acids with copper as the central metal have been reported. Davies et al. and Ghosh et al. independently developed a bis(oxazoline) ligand prepared from aminoindanol, and applied the copper complex of this ligand to the asymmetric Diels-Alder reaction. Davies varied the link between the two oxazolines and found that cyclopropyl is the best connector (see catalyst 26), giving the cycloadduct of acryloyloxazolidinone and cyclopentadiene in high optical purity (98.4% ee) [35] (Scheme 1.45). Ghosh et al., on the other hand, obtained the same cycloadduct in 99% ee by the use of unsubstituted ligand (see catalyst 27) [36] (Scheme 1.46, Table 1.19). 

Nickel atoms have also been allowed to react with C2H4 under cryogenic conditions (101,123). Depending on the metal-concentration conditions and the deposition temperature, either mononuclear species, Ni(C2H4) , n = 1-3(123), or multinuclear species, Ni2(C2H4) ,m = 1-2, and Ni3(CjH4)i, may be isolated. Unlike the copper complexes, these species are all colorless the mononuclear ethylene complexes each dis-... 

From culture of Streptomyces verticillus by ion-exchange adsorption and column chromatographic purification (on alumina) via the copper complex. 

The rate of peroxide decomposition and the resultant rate of oxidation are markedly increased by the presence of ions of metals such as iron, copper, manganese, and cobalt [13]. This catalytic decomposition is based on a redox mechanism, as in Figure 15.2. Consequently, it is important to control and limit the amounts of metal impurities in raw rubber. The influence of antioxidants against these rubber poisons depends at least partially on a complex formation (chelation) of the damaging ion. In favor of this theory is the fact that simple chelating agents that have no aging-protective activity, like ethylene diamine tetracetic acid (EDTA), act as copper protectors. 

There are scattered reports on isocyanide complexes of other metals including copper and gold, vanadium, and several lanthanides and actinides. 

The use of chiral bis(oxazoline) copper catalysts has also been often reported as an efficient and economic way to perform asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines with conjugated dienes [81], with the main focus on the application of this methodology towards the preparation of biologically valuable synthons [82]. Only some representative examples are listed below. For example, the copper complex 54 (Scheme 26) has been successfully involved in the catalytic hetero Diels-Alder reaction of a substituted cyclohexadiene with ethyl glyoxylate [83], a key step in the total synthesis of (i )-dihydroactinidiolide (Scheme 30). 

Table 8 Results of cyclopropanation reactions with copper complexes exchanged on anionic supports ...

The reaction used to test these solid catalysts was the aziridination of styrene with AT-tosyliminophenyliodinane (Phi = NTos) (Scheme 10). In most cases, enantioselectivities were low or moderate (up to 60% ee). The loss of enantioselectivity on changing from ligand 11a to ligand 12 was attributed to the fact that ligand 12 is too big for the copper complex to be accommodated into the zeolite supercages. Further studies carried out with hgands 11a and 11b [62] demonstrated that the reaction is more enantioselective with the supported catalyst (82% ee with 11a and 77% ee with 11b) than in solution (54% ee with 11a and 31% ee with 11b). This trend supports the confinement effect of the zeolite structure on the stereoselectivity of the reaction. 

Carbonyl- and imino-ene reactions were also catalyzed by the bis(oxazo-line)-copper complexes of ligands 6a, 6b and 11b supported on zeoHte Y (Scheme 13) [69]. The enantioselectivities obtained with the supported catalysts were similar or better than those obtained in homogeneous phase with the same ligands. Some relevant examples are shown in Table 12. 

Table 12 Results of reactions of ethyl glyoxylate with different alkenes, catalyzed by several bis(oxazoline)-copper complexes immobilized on Y zeolite...

This group showed that isolable silver(I) diaminocarbene complexes can be use in situ instead of free carbenes, to generate the copper carbene complex. The silver salts that precipitates during the formation of the copper complex have not any negative effect on the conversion. This method is advantageous since most of the silver complexes are isolable, air-stable and easily obtained by treatment of the corresponding imidazohnium salt by 0.5 equiv of silver oxide (Scheme 53). The solid structure of 78 was analyzed by X-ray diffraction. 

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