Copper complexes magnetic properties

ESEEM has been applied to the study of surface complexes, coordination of water in metmyoglobin, the structures of ligands in a copper protein, magnetic properties of electronic triplet states, and solitons in polyacetylene. 

Complexes. The structure of an n a charge-transfer complex between quinoxaline and two iodine atoms has been obtained by X-ray analysis and its thermal stability compared with those of related complexes. The hydrogen bond complex between quinoxaline and phenol has been studied by infrared spectroscopy and compared with many similar complexes. Adducts of quinoxaline with uranium salts and with a variety of copper(II) alkano-ates have been prepared, characterized, and studied with respect to IR spectra or magnetic properties, respectively. 

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... 

Figure 28 The temperature variable magnetic properties of copper(II) complexes (a) paramagnetic, t ia. T (b) paramagnetic, x vs. l/T (c) ferromagnetic, % vs. T and (d) antiferromagnetic, x vs. T...

Multimetallic complexes (tetranuclear and pentanuclear with complicated structures) of these ligands which could have unique magnetic properties were prepared and studied. It is noted [125a] that, in the copper complex with H2L, Cu5(0H)2(L)2(N03)4, all magnetic interactions within the complex unit H2L appear to be antiferromagnetic, as well as in copper complexes with two other ligands, [Cu(HL1)(N03)]4 and [Cu2(L2)(OAc)2]2 [187,188],... 

Considering the special bioactive and biocatalytic functions of copper(II) carboxylate complexes,[9] along with the magnetic properties and various coordination fashions of Cu(II) ion,[10-12] we focused our work on the Cu(II) and H4btec system. Based on the layer structure of [Cu2(btec)(H20) -4H20] (1),[13] in which the Cu(ll) atom with bi-pyramidal configuration is coordinated by two monodentate carboxyl O atoms and three aqua molecules, part of the coordinated aqua molecules of Cu(II) is possible to be replaced by some bridging spacers, such as pyrazine, 4,4 -bipyridine (4,4 -bpy) and the related species, and to construct 2-D and 3-D open-frameworks with variable cavities and channels. 

Buchanan, R. M., Wilson-Blumenberg, C., Trapp, C., Larsen, S. K., Green, D. L., and Pierpont, C. G., 1986, Counterligand Dependence of Charge Distribution in Copper-Quinone Complexes. Structural and Magnetic properties of (3,5-Di-ferf-butylcatecholato)(bipyri-dine)copper(II), Inorg. Chem. 25 3070-3076. 

The majority of cyanide-bridged dinuclear complexes described for the combination of metal ions belong to the biologically relevant class of Cu —Fe dimers. These compounds serve as models for the binuclear cyanide-inhibited site of cytochrome c oxidase, an enzyme that contains the heme-copper active site responsible for the O2 reduction chemistry (59). The lethal toxicity of cyanide was traced to its irreversible binding and inhibition of this active site in the enzyme (60). The biologically relevant aspects of these complexes were the subject of many reports (61,62). Our interest is in describing their crystal structure, which will be correlated to the magnetic properties in a later section. 

The magnetic properties of complexes of these anions have been studied, particularly copper(n) complexes, and have been compared with the results obtained with analogous oxalato complexes the squarato and croconato bridges are... 

Although the focus of this section has primarily been on iron and copper complexes, probably the most important transition metals biologically studied by the MCD technique, variable temperature and field dependence studies have also been carried out for complexes of other transition metals such as cobalt and manganese and the techniques described for iron and copper can easily be applied to other metals based on the nature of the ground state. MCD spectroscopy has the key advantage, over other techniques used to study bulk magnetic properties of an entire sample, that spectral bands associated with specific mefal cenfers can be sfudied in isolation. 

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