Copper complexes molecular structures

In contrast to the well-established methods for identifying and quantifying naturally occurring chlorophylls, very few reports concern quantitative analysis of chlorophyllin copper complexes in color additives and in foodstuffs. Analytical methods proposed are based on spectral properties, elemental analysis, chromatographic separation, and molecular structure elucidation or a combination of these procedures. 

Benouazzane, M., Coco, S Espinet, P. and Barbera, J. (2001) Supramolecular organization in copper(I) isocyanide complexes Copper(I) liquid crystals from a simple molecular structure. Journal of Materials Chemistry, 11, 1740-1744. 

A series of copper(II) complexes with ring-substituted phen-ligands have been synthesized and their molecular structural and electronic structural properties have been investigated.246 Each structure ((280) r = 0.72, (281) r = 0.81, (282) r = 0.88, (283) r = 0.83, and (284) r = 0.68) is characterized by a distorted trigonal-bipyramidal arrangement of ligands around copper. 

In their pursuit of determining solution structures of dinuclear copper complexes as carried out for complex (29) (Section 6.6.3.1.1). Comba reported complex (431) (r = 0.02 Cu-Cu 6.9 A, comparable with the values of 7.2 A predicted by molecular mechanics calculations and 6.7 A obtained from the simulated EPR spectrum).54 They reported369 complexes (432) (square planar) and (433) (Cu-Cu 3.35 A) as well. As part of studying magnetic properties of mono-, di-, and... 

The complex trans-[Cun(hfac)2(TTF—CH=CH—py)2](BF4)2-2CH2Cl2 was obtained after 1 week of galvanostatic oxidation of Cun(hfac)2(TTF CH=CH py)2 [61]. The molecular structure of the copper complex is identical to its neutral form. There is one TTF CH=CH py molecule per BF4 and one dichloromethane solvent molecule. The copper is located at the center of a centrosymetric-distorted octahedron two TTF CH=CH py ligands in trans- conformation are bonded to Cun by the nitrogen atoms of the pyridyl rings. From the stoichiometry, the charge distribution corresponds to fully oxidized TTF CH=CH—py+" radical units. 

TPMA ligand typically coordinates to the copper center in a tetradentate fashion, similarly to Me6TREN [117]. However, the role of counterion coordination (in particular Br and Cl ) in these complexes still remains very unclear. Recently, we were able to isolate and structurally characterize neutral CuI(TPMA)Cl [118] and CuI(TPMA)Br [119] complexes. To our surprise, both complexes were pseudopenta-coordinated (Fig. 6). In CuI(TPMA)Cl, the copper ion was coordinated by four nitrogen atoms with bond lengths of 2.0704(11), 2.0833(11), 2.0888(11) A for the equatorial Cu-N, and 2.4366(11) A for the axial Cu-N bonds, and a chlorine atom with a bond length of 2.3976(4) A. The molecular structure of Cu (TPMA)Br was similar to the structure of Cu (TPMA)Cl and the complex was also found to be pseudopentacoordinated in the solid state due to the coordination of TPMA (Cu-N... 

In the following sections we shall discuss (i) the structure and behaviour of the various copper complexes with the ligands listed in scheme 2 (ii) the activities of the polymeric catalysts in comparison with the low molecular weight analogs (iii) the effect of the degree of substitution, a, on the activities of the polymeric catalysts. 

Figure 10 shows the molecular structures of both the copper(II) and copper(I) congeners. As seen, the copper(II) complex possesses an octahedral S402 coordination, whereas the copper(I) complex assumes a tetrahedral S4 coordination releasing the bonding with the two oxygen atoms. 

Let us now pass to the commonest tetracoordinated copper complexes. Figure 117 shows the molecular structure of the Cu(II)-2-dipyridylamine... 

More advanced semiempirical molecular orbital methods have also been used in this respect in modeling, e.g., the structure of a diphosphonium extractant in the gas phase, and then the percentage extraction of zinc ion-pair complexes was correlated with the calculated energy of association of the ion pairs [29]. Semiempirical SCF calculations, used to study structure, conformational changes and hydration of hydroxyoximes as extractants of copper, appeared helpful in interpreting their interfacial activity and the rate of extraction [30]. Similar (PM3, ZINDO) methods were also used to model the structure of some commercial extractants (pyridine dicarboxylates, pyridyloctanoates, jS-diketones, hydroxyoximes), as well as the effects of their hydration and association with modifiers (alcohols, )S-diketones) on their thermodynamic and interfacial activity [31 33]. In addition, the structure of copper complexes with these extractants was calculated [32]. 

Fig. 19.30 Molecular structure of copper complex of D-penknUamme. The ICu Cu pefl(cillajnrnate) 2CI ion (a) the central cluster of Cu and ligating atoms only, (b) the entire ion with the centra] duster oriented as In (a). From Biricer. P. J. M. W. L. Freeman. H. C. Chem. Commtm. 1976.312. Reproduced with permission.)...

For the mononuclear complexes of the copper(II) ion, as summarized in the molecular structures (174)-(255). Tables 21-27 and Figures 17-25, the following generalizations may be made ... 

Reactions of limited proportions of amine and phosphine Lewis bases with non-molecular copper and silver halides generate crystalline cubanes. Crystallographic determinations of molecular structure have been reported for at least 31 complexes with cf or d10 metal configurations, spanning the following types or homologous series of compounds. Compilations of data occur in references 157, 158 and 167. 

Mordant dyes have hydroxy groups in their molecular structure that are capable of forming complexes with melals. Although a variety of metals such as iron, copper, aluminum, and cohalt have been used, chromium is most preferable as a mordant. Alizarin or Cl Mordant Red 11 (Cl 38000). the principal component of the natural dye obtained from madder root, is the most typical mordant dye. Many murdant dyes have given way to the vat or the azoic dyes, which arc applied by much simpler dyeing procedures. 

---