Copper !® complexes

The dimethylimidazolate and the methylimidazolate complexes undergo a chemically reversible two-electron oxidation in dichloromethane at the same potential value E° (0/2- -) = -fO.56 V), which demonstrates the lack of interaction between the two ferrocenyl centers of these species. Nevertheless, if one considers that free 

As in the case of the corresponding cobalt and nickel complexes, this copper complex undergoes a ferrocene-based two-electron oxidation in DMF in the same range of potential values (F° = -f 0.53 V) [119]. 

The similar complex [7,16-bis(ferrocenylcarbonyl)-l,4,10,13-tetrathia-7,16-diaza-cyclooctadecane]copper(i), [CuL ] has also been prepared [186]. 

Another copper(i) complex possessing tetrahedral coordination is shown in Fig. 7-66 [187]. The central copper(i) ion is coordinated both to one l,l -bis(diphenyl-phosphino)ferrocene molecule (dppf) and one l,l -bis(oxodiphenylphosphoranyl)-ferrocene molecule (odppf). All the cyclopentadienyl rings are planar and mutually staggered (A/C) or half-staggered (B/D). 

2-dichloroethane solution the complex displays two subsequent one-electron oxidation steps, reversible in character, that are assigned to dppf/[dppf] ( = -1-0.78 V) and odppf/[odppf] (E° = -f 1.16 V), respectively. In agreement with the strong bonding between the metal and the two ferrocene fragments, the free ferrocenylphosphines are significantly easier to oxidize [ (dppf/[dppf] ) = -i- 0.64 V E° (odppf/[odppf]+) = -1-0.94 V) [187]. 

As illustrated in Fig. 7-69, the dication undergoes a single-step three-electron oxidation process at E° = +0.92 V (ds. SCE) [190]. 

It is easy to imagine that the commonest oxidation states of copper are Cu(II) (d9) and Cu(I) (d10), but, as we shall see, the oxidation state III is not so rare. 

X-Ray structure of the dication [Cu(dpa)2]2+ Cu-N average bond length = 1.96 A. Dihedral angle between the two CuN2 planes = 55.60 

It displays two successive reductions, corresponding to the sequence Cu(II)/Cu(I)/Cu(0). The first step (E° = + 0.19 V) is chemically reversible (ipJipc = 1) but electrochemically quasireversible (A2sp = 145 mV, at 0.2 V s 1) the second step is irreversible ( p = -0.65 V). The appearance of peak C in the backscan reveals, by its characteristic pointed lineshape, the presence of a process known as anodic stripping . This consists of the sudden reoxidation of the metallic copper that has been deposited on the electrode surface during the Cu(I)/Cu(0) reduction. 

The corresponding Cu(I) complex, [Cu(dpa)2] +, has been isolated and its structure solved. It maintains a tetrahedral geometry, though with a few significant variations in the structural parameters (Cu-N = 2.02 A dihedral angle between the two CuN2 planes = 73.3°).176 

If one makes the reasonable assumption that the quasireversibility of the Cu(II)/Cu(I) reduction is due to the energy barrier of the structural reorganization, one may infer that the addition of an electron causes an increase in the Cu-N bond distances by about 0.6 A and the dihedral angle between the two CuN2 planes approaches more closely that of a perfectly tetrahedral geometry 

Tlie most common catalysts for ATRP are complexes based on a copper(T) halide and nitrogen based ligand(s). Various ligands have been employed and those most frequently encountered are summarized in Table 9.5. Typically, four nitrogens coordinate to copper. The bidentate bipyridyl (bpy) ligands 132-133 are known to form a 2 1 complex. The tetradentate ligands are expected to form a 1 1 complex. 

Certain multidentate ligands also provide for better solubility. Cu complexes formed with tetramcthylethylcncdiamine (TMEDA), N,N,N ,N ,N -pentamethyldiethylenetriamine (PMDETA, 140) and 1,1,4,7,10,10-hcxamcthyltricthylcnctctraminc (HMTETA, 144) and MC(,TREN (145) have been found effective. Tran.sfer to ligand during MMA polymerization has been reported as a side reaction when PMDETA is used.  

Percec and coworkers reported in litu fonnation of active CuCl/CuCL catalyst from the initiator, CuiO, Cu 0) and combinations of these in conjunction with ligand (bpy) and various polyelhers or ethylene glycol and suggested that improved control was obtained under these conditions. 

Supported copper catalysts have also been described/  

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A substantial fraction of the named enzymes are oxido-reductases, responsible for shuttling electrons along metabolic pathways that reduce carbon dioxide to sugar (in the case of plants), or reduce oxygen to water (in the case of mammals). The oxido-reductases that drive these processes involve a small set of redox active cofactors , that is, small chemical groups that gain or lose electrons. These cofactors include iron porjDhyrins, iron-sulfur clusters and copper complexes as well as organic species that are ET active. 

Crystal stmctures of complexes of copper(II) with aromatic amine ligands and -amino acids " " and dipeptides" have been published. The stmctures of mixed ligand-copper complexes of L-tryptophan in combination with 1,10-phenanthroline and 2,2 -bipyridine and L-tyrosine in combination with 2,2 -bipyridine are shown in Figure 3.2. Note the subtle difference between the orientation of the indole ring in the two 1,10-phenanthroline complexes. The distance between the two... 

Fortunately, in the presence of excess copper(II)nitrate, the elimination reaction is an order of magnitude slower than the desired Diels-Alder reaction with cyclopentadiene, so that upon addition of an excess of cyclopentadiene and copper(II)nitrate, 4.51 is converted smoothly into copper complex 4.53. Removal of the copper ions by treatment with an aqueous EDTA solution afforded in 71% yield crude Diels-Alder adduct 4.54. Catalysis of the Diels-Alder reaction by nickel(II)nitrate is also... 

Fonnation of a complex with a copper cation only further stimulates this behaviour. As a result, S.lg is almost completely bound to the micelles, even at low concentrations of Cu(DS)2. By contrast, the reaction of 5.1 f still benefits from an increasing surfactant concentration at 10 mM of Cu(DS)2. In fact, it is surprising that the reaction of this anionic compound is catalysed at all by an anionic surfactant. Probably it is the copper complex of 5.If, being overall cationic, that binds to the micelle. Not surprisingly, the neutral substrate S.lc shows intermediate behaviour. 

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. 

Copper. Some 15 copper compounds (qv) have been used as micronutrient fertilizers. These include copper sulfates, oxides, chlorides, and cupric ammonium phosphate [15928-74-2] and several copper complexes and chelates. Recommended rates of Cu appHcation range from a low of 0.2 to as much as 14 kg/hm. Both soil and foHar appHcations are used. 

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. ... 

Many electroless coppers also have extended process Hves. Bailout, the process solution that is removed and periodically replaced by Hquid replenishment solution, must still be treated. Better waste treatment processes mean that removal of the copper from electroless copper complexes is easier. Methods have been developed to eliminate formaldehyde in wastewater, using hydrogen peroxide (qv) or other chemicals, or by electrochemical methods. Ion exchange (qv) and electro dialysis methods are available for bath life extension and waste minimi2ation of electroless nickel plating baths (see... 

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). 

In acidic solution, the degradation results in the formation of furfural, furfuryl alcohol, 2-furoic acid, 3-hydroxyfurfural, furoin, 2-methyl-3,8-dihydroxychroman, ethylglyoxal, and several condensation products (36). Many metals, especially copper, cataly2e the oxidation of L-ascorbic acid. Oxalic acid and copper form a chelate complex which prevents the ascorbic acid-copper-complex formation and therefore oxalic acid inhibits effectively the oxidation of L-ascorbic acid. L-Ascorbic acid can also be stabilized with metaphosphoric acid, amino acids, 8-hydroxyquinoline, glycols, sugars, and trichloracetic acid (38). Another catalytic reaction which accounts for loss of L-ascorbic acid occurs with enzymes, eg, L-ascorbic acid oxidase, a copper protein-containing enzyme. 

Direct Blue 218 had reported sales of 623 t valued at 4.4 million ia 1987. It is produced from Direct Blue 15 (76) by metallizing and elimination of methyl groups from the methoxide to form the copper complex. Direct Blue 15 (76) is prepared by coupling o-dianisidine [119-90-4] to two moles of H-acid (4-amiQO-5-hydroxy-2,7-naphthalenedisulfonic acid) under alkaline pH conditions. Other important direct blues iaclude Direct Blue 80 (74), (9-dianisidine coupled to two moles of R-acid (3-hydroxy-2,7-naphthalenedisulfonic acid [148-75-4]) followed by metallizing to form a bis copper complex, and Direct Blue 22 (77), an asymmetrical disazo dye, prepared by coupling o-dianisidine to Chicago acid [82-47-3] and 2-naphthol. Direct Blue 75 (78) is an example of a trisazo dye represented as metanilic acid — 1,6-Q.eve s acid — 1,6-Q.eve s acid — (alb) Ai-phenyl J-acid. 

The Colour Index (up to June 1991) Hsts 21 direct violets with disclosed chemical constitutions. Commercially important are Cl Direct Violet 9 [6227-14-1] (79) (Cl 27885) (sulfanihc acid coupled to cresidiue followed by alkaline coupling to V-phenyl J-acid) and Cl Direct Violet 66 [6798-03-4] (80) (Cl 29120) (a copper complex of 2-arniao-l-phenol-4-sulfonarnide (2 mol) coupled to 6,6 -imiQobis-l-naphthol-3-sulfonic acid). 

Chiorophyllin—copper complex, oil soluble—The chlorophyllin is obtained by extraction from a mixture of fescue and rye grasses. The chlorophyll is... 

Potassium sodium copper chlorophyllin (chiorophyllin—copper complex)—A green-black powder obtained from chlorophyll by replacing the methyl and phytyl ester groups with alkaH and replacing the magnesium with copper. The source of the chlorophyll is dehydrated alfalfa. 

Forma n dyes bear a formal resemblance to a2o dyes, since they contain an a2o group but have sufficient stmctural dissimilarities to be considered as a separate class of dyes. The most important forma2an dyes are the metal complexes, particularly copper complexes, of tetradentate forma2ans. They are used as reactive dyes for cotton (81) is a representative example. 

Pyridazines form complexes with iodine, iodine monochloride, bromine, nickel(II) ethyl xanthate, iron carbonyls, iron carbonyl and triphenylphosphine, boron trihalides, silver salts, mercury(I) salts, iridium and ruthenium salts, chromium carbonyl and transition metals, and pentammine complexes of osmium(II) and osmium(III) (79ACS(A)125). Pyridazine N- oxide and its methyl and phenyl substituted derivatives form copper complexes (78TL1979). 

Porphyrin, octaethyl-, copper complex cyclic voltammetry, 4, 399 <73JA5140)... 

Isoxazole, 4-methyI-3,5-diphenyI-bromination, 6, 51 Isoxazole, 3-methyI-4-nitro-5-styryI-photolysis, 6, 14 Isoxazole, 3-methyI-5-phenyl-copper complexes... 

Hydrometallurgy Department, R D Division, vSarcheshmeh Copper Complex, Rafsanjan,Kerman, Iran sagedeh2 yahoo.com... 

Simultaneous detenuination of Cu and Zn in the form of coloured PAR complexes is performed at pH 10 in the presence of pyrophosphate which binds the admixtures of Al, Fe and Mn into the inactive complexes. The measurements of the change in the optical density are made at 520 and 550 nm before and after the destmction of the complexes by EDTA, or at 530 nm before and after the destruction of the copper complexes by the thioglycolic acid and the destmction of the zinc complexes by EDTA. The detection limit for Cu is 2-5, for Zn - 3 p.g/diW. The application of these methodics at pH 8 enables one to determine simultaneously Cu and Zn at high excess of the latter. 

Copper alloys are attacked at high pH. However, attack is usually caused not by elevated pH alone but because of copper complexation by ammonia or substituted ammonium compounds. In fact, copper resists corrosion in caustic solutions. For example, corrosion rates in hot caustic soda may be less than 1 mil/y (0.025 mm/y). 

The copper complex 1s available from Strem Chemicals, Inc., under the name cuprous triflate (benzene complex). The checkers recommend handling the material In a dry box because of Its high moisture and air sensitivity. 

Neutralization to phenolphthalein is satisfactory, but a glass electrode might give better results. Hydroxyurea is decomposed very rapidly in aqueous acidic medium, whereas its metallic salts (sodium or the copper complex salts) are stable. 

The chromatograms stained with ninhydrin are immersed in the reagent solution for 1 s or sprayed evenly with it and then placed in the free half of a twin-trough chamber containing 25% ammonia solution. Apart from proline and hydroxyproline, which yield yellow copper complexes, all the amino acids yield reddish-colored chromatogram zones [3],... 

The copper complex is very stable at neutral pH, but it fades very rapidly in the presence of hydrogen ions. Other complex formers such as tartaric acid or citric acid and thiourea interfere with the reaction and, therefore, should not be included in mobile phases used for the separation of amino acids [3]. 

The substances listed above form colored copper complexes. 

Making and breaking the dioxygen 0—0 bond with participation of synthetic copper complexes with heterocyclic ligands 97ACR227. 

Photoprocesses of RNA-bound copper complexes with macroheterocyclic ligands 98CRV1201. 

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. 

Increased interest in the chemistry of ylides has produced X-ray structures for compounds 123 (R = OMe) (91T5277) and 138 (92H(34)1005), while possibilities of complex formation have led to structures for bidentate copper complex of 135 (94JCS(D)2651), monodentate copper complex of the 3-phenyltria-zolopyridine 139, monodentate (through N2) dinitrato ligand of 3-methyl-triazolopyridine 140 (99MI4), and dinitrato bidentate copper complex of... 

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