Complexes with Cu

The concentrations of Fe + and in a mixture can be determined following their reaction with hexacyanoruthenate (II), Ru(CN)5 , which forms a purple-blue complex with Fe + Q max = 550 nm), and a pale green complex with Cu + ( max = 396 nm)d The molar absorptivities cm ) for the metal... 

This experiment describes a standard multicomponent analysis for two analytes based on measuring the absorbance at two wavelengths. Hexacyanoruthenate(II) is used as a complexing agent, forming a purple-blue complex with Fe(III) and a pale green complex with Cu(II). 

Hydroxyquinoline forms the complex with Cu(II) in ratio 1 1 at pH 5-7. The composition of the complex is changed on 1 2 at pH>7. 8-Hydroxy-quinoline accepts bromine therefore its excess has been removed with NaOH solution. The complex was extracted with chloroform. It was shown that double extraction was enough to extract the complex. The detection limit is 5x10 M during 10c and at current generation IxlO A. 

Recently, a reagent that reacts more efficiently with Cn than Folin-Ciocalteau reagent has been developed for protein assays. Bieinehoninie aeid (BCA) forms a purple complex with Cu in alkaline solution. 

Two classes of complexes with Cu(III) are known. The first type contains the cation [Cu(R2 c)2], the second type has the general formula X2Cu(Bu2c/fc)(X = Cl, Br). 

Notably, dimerization of ligands was not observed when the complexes with Cu(I) salts and AgN03 were formed. Metal atoms were expected to coordinate nitrogen [Eq. (151)]. 

The presence of substituents and the use of pyridine as solvent changes the ratio of ligands. In the case of donor or weak acceptor substituents the formation of complexes with Cu(I) takes place, stable crystalline compounds being obtained only in the presence of pyridine. In all the cases copper forms complexes with one phosphorus ligand but the number of pyridine molecules varies from 1 to 3 [Eq. (155)]. 

Dithiocarbamates and xanthates form particularly stable, neutral complexes with Cu(II), Cd(II) (and also Ni, Hg, Pb), which are membrane permeable and increase the apparent bioaccumulation of these metals [13]. In the series of sulfoxine, oxine, and chloroxine, the hydrophobicity of the neutral and the charged form, as well as of the Cu complex, increases. While the sulfoxine is not hydrophobic and does not modulate copper toxicity [220], the Cu-oxine complex is hydrophobic with an octanol-water partition constant, log Kok, of 1.7 [221] or 2.6 [222]. Chloroxine can be assumed to be even more hydrophobic, but so far its influence on uptake and toxicity has not been investigated. Uptake of Cu2+ into unilamellar liposomes was increased in the presence of 8-hydroxy-chinoline, and decreased again after adding HA [223],... 

The block copolymer was complexed with Cu(II) ion in methanol, then the methanol was evaporated to dryness. The Cu complexed block copolymer was soluble in water. Its spectroscopic property showed that the structure and stability of the Cu complex were similar to those of the complex in a benzene solvent. But the reactivity of the Cu complex in the block copolymer could not be examined. The Cu complex was occuluded so tightly in the... 

In this study, we report synthesis of a new thiourea derivative (2) which contain crown ether and phenanthroline ring by the reaction of 5-amino-1,10-phenanthro-line with 15-isothiocyanatobenzo[15-crown-5] (1) (Fig. 43.1) and its complex with Cu(I) is obtained. The structures of the ligand and the complex were determined by their elemental analysis, UV-vis, FTIR, H NMR (DMSO-d ), C NMR (DMSO-dg) and Mass spectra (LC-MS). 

MALDl-TOF mass spectrometry (MS) has also been used to characterize PAM AM dendrimer composition with and without added Cu + [98]. linear-mode MALDI-TOF mass spectra of G2 and G3, and their complexes with Cu + ions, are shown in Fig. 9. 

TABLE 8.1. Stability Constants (log p and pA Values) of Kanamycin B, Amikacin and Tobramycin Complexes with Cu +... 

Bleomycin is a naturally occurring fermentation product of Streptomyces verticillus. It is a basic glycoprotein, complexed with Cu++. It intercalates between DNA base pairs, and it also chelates iron, generating oxygen radicals which further damage the DNA. It is the only cell-cycle specific agent among the antibiotics as it causes accumulation of cells in the G2 phase of the cell cycle. 

Although thiocyanate also forms an insoluble complex with Cu(I) pKgp for CuSCN = 12.7) [172], the compound is more soluble than CuCN as reflected hy the less negative standard potential for electrodeposition [173] ... 

Complexes with Acetate and Other Common Brensted Bases Many reactions of copper tend to be conducted in the range of pH 4.0-5.5 to avoid possible formation of hydroxycopper species. This is a range in which acetate is the most commonly used buffer. Unfortunately, acetate (Ac ) is a very poor choice as it forms stronger complexes with Cu(II) than with any other divalent metal ion except Hg(II). The stepwise equihhrium constants for the formation of Cu(Ac)+, Cu(Ac)2, Cu(Ac)3, and Cu(Ac)4 are 50, 10, 2.5, and 0.6, respectively [176]. 

Thiabutadienes undergo highly enantioselective hDA reactions in the presence of homochiral bis(oxazoline) and bis(imine) complexes with Cu and Ni (Scheme 37) <99CC1001>. Homochiral camphor-based thiabutadienes show good exo selectivity and give rise to bomene ring-fused dihydrothiopyrans (Scheme 38) <99TL8383>. 

The C-substituted chelates provide higher rotational barriers to ring openings giving smaller values of k. Furthermore, C-tetraMeen forms a thermodynamically more stable complex with Cu than does en. 

Hydroxybenzothiazole (10) has the same chelating group as oxine (7) and forms insoluble complexes with Cu, Ni, and Zn, which are relatively more soluble, probably because the sulfur atom tends to form hydrogen bonds with the solvent. 

Alkali dithioformates can be prepared according to reaction (10) in a methanolic medium. The unstable free monomeric add, which trimerizes within a few minutes, is formed when an aqueous solution of these compounds is treated with HC1. The trimeric acid turns into the polymeric product (24) in DMF or DMSO. The alkali metal compounds are light and oxygen sensitive. Its complexes with Cu", Tl1, In1" and PbD are stable, whereas the Ag1, FeD, Co" and Ni compounds decompose and give the metal sulfides.1... 

Fe—Fe bond present in 58 is bridged by two carbonyls, contrasting with the absence of bridging carbonyls in 56. The tin analogue of 58, [Sn Fe2(CO)8 - Fe(CO)4 2]2, 59, has also been synthesized by a similar route (71), and oxidation by Cu(l) proceeds in a similar manner to the example for lead and provides another synthetic route to 54. With germanium, however, the more condensed cluster species [Ge Fe3(CO)10 Fe(CO)4 ]2 , 60, is formed (77), although oxidation of this complex with Cu(I) affords 55, analogous to the formation of 54 and 56 from 59 and 58, respectively. 

Reaction of Cytochrome cIinn with Bis(ferrozine)copper(II) Knowledge of the redox properties of cytochrome c was an encouragement to initiate a kinetics investigation of the reduction of an unusual copper(II) complex species by cyt c11. Ferrozine (5,6-bis(4-sulphonatophenyl)-3-(2-pyridyl)-1,2.4-triazine)286 (see Scheme 7.1), a ligand that had come to prominence as a sensitive spectrophotometric probe for the presence of aqua-Fe(II),19c,287 forms a bis complex with Cu(II) that is square pyramidal, with a water molecule in a fifth axial position, whereas the bis-ferrozine complex of Cu(I) is tetrahedral.286 These geometries are based primarily upon analysis of the UV/visible spectrum. Both complexes are anionic, as for the tris-oxalato complex of cobalt in reaction with cytochrome c (Section 7.3.3.4), the expectation is that the two partners will bind sufficiently strongly in the precursor complex to allow separation of the precursor formation constant from the electron transfer rate constant, from the empirical kinetic data. 

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