Copper complexes bridging

Fig. 25 Several dinuclear nickel and copper complexes bridged by a tetrathiooxalato ligand...

Scheme 61).22 149 150 152 229 230 The methylene-bridged bis(oxazoline)s (70) can afford either neutral copper complexes of the semicorrin type (72) or cationic copper complexes (73). Cyclopro-panation with copper complexes of type (70) shows similar stereochemistry to that with the corresponding copper semicorrin complexes.229-231 Alternatively, bis(oxazoline) ligand (71), bearing... 

X-ray crystallographic data has become available on the commercially important 1 1 copper complex azo dyes. The symmetrical dihydroxyazo ligand (16) forms the 1 1 square planar complex (17).13 A pyridine molecule occupies the fourth coordination site since this complex facilitated the formation of crystals suitable for X-ray diffraction. The complex (17) actually exists as an unusual trimer which is held together by long bridging interactions between the copper atom in one molecule and one of the hydroxy oxygen atoms from the adjacent molecules. 

The same complex could be obtained starting from CuC and subsequent substitution of both bridged chlorides by adding hydroxyl ions. Scheme 3 describes the formation and interconversion of both binuclear copper complexes. 

The complexation of anionic species by tetra-bridged phosphorylated cavitands concerns mainly the work of Puddephatt et al. who described the selective complexation of halides by the tetra-copper and tetra-silver complexes of 2 (see Scheme 17). The complexes are size selective hosts for halide anions and it was demonstrated that in the copper complex, iodide is preferred over chloride. Iodide is large enough to bridge the four copper atoms but chloride is too small and can coordinate only to three of them to form the [2-Cu4(yU-Cl)4(yU3-Cl)] complex so that in a mixed iodide-chloride complex, iodide is preferentially encapsulated inside the cavity. In the [2-Ag4(//-Cl)4(yU4-Cl)] silver complex, the larger size of the Ag(I) atom allowed the inner chloride atom to bind with the four silver atoms. The X-ray crystal structure of the complexes revealed that one Y halide ion is encapsulated in the center of the cavity and bound to 3 copper atoms in [2-Cu4(//-Cl)4(//3-Cl)] (Y=C1) [45] or to 4 copper atoms in [2-Cu4(/U-Cl)4(/U4-I)] (Y=I) and to 4 silver atoms in [2-Ag4(/i-Cl)4(/i4-Cl)] [47]. NMR studies in solution of the inclusion process showed that multiple coordination types take place in the supramolecular complexes. 

The insolubility of the Cu(I) halide salts, as well as the possibility of /x-halo-bridge formation between two copper atoms (as discussed later) or between the copper complex and the electrode surface, suggests that the presence of hahdes may alter the electrochemical properties observed for copper-containing solutions. 

Several other peroxo bridged complexes have been lately synthesized53-54 simply by reacting appropriate precursors and dioxygen, as shown in equation 7 for di-Ir(II) complex 5, with bis(diphenylphosphinomethane) dppm, and in equation 8 for a dicopper(II) species 6. The same procedure has been also applied to obtain a peroxo bridged heme-copper complex 755 (equation 9). 

No modification is observed in the dimensionality compared with that of the parent gold cyanide complex, but an increment in the thermal stability is described in the final compound. In the structure of [Cu(tmeda)][Au(CN)2]2 (tmeda = N,N,N, N -tetramethylenediamine) aurophilic interactions connect ID chains which contain copper(II)-bridging and pendant [Au(CN)2] units. In this case the aurophilic interactions increase the structural dimensionality from one to three. The compound is synthesized by reaction of Cu(C104)2.6H20, tmeda (tetramethylethylenediamine) and K[Au(CN)2]. The structure of Au2Cu(CN)4(tacn)] (tarn = 1,4,7- triazacyclono-nane) contains two different sort of chains. One of them contains gold atoms in an ABCDABCD- pattern (Figure 2.16a), and the other is built from two kinds of... 

Special features strongly related to the compactness of the phenylene-bridged knots were also observed during the photophysical studies. All die compounds, as usual for copper complexes with phenanthroline-type ligands [116, 117], exhibit MLCT luminescence in CH2C12 at room temperature. Only one emission band, assigned to the lowest MLCT excited state, is observed even for the complexes con-... 

In order to introduce more flexibility into the structure of dinuclear copper(II) complexes, bridging ligands of type Y, such as p-XYLpy2 (261),595 have been combined with simple anion bridging ligands, such as Cl-, OH-, (CN)-, (OPh)- and (N3)-, to produce very asymmetric... 

Sulfur ligands, 633-655 coordination ability, 516 Sulfur monoxide metal complexes instability, 636 Superoxide dismutase, 773 copper complexes, 772 Superoxo complexes, 315-330 binuclear, 323, 325 reactions, 330 bridged... 

The copper-porphyrin complex gives cation radicals with significant reactivity at the molecular periphery. This reactivity appears to be that of nucleophilic attack on this cation radical, which belongs to the -rr type (Ehlinger Scheidt 1999). A new bifunctional tetrathiafulvalene-type donor molecule (D-ct-D) with a copper iodine bridge has recently been synthesized. Its cation radical salt, (D-variable valence (Ramos et al. 1997). 

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