Copper charge-transfer complexes

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. 

Charge transfer complexes have also been investigated as the most attractive candidate materials for high-density electrical data storage.76,77 For instance, sil-ver-tetracyanoquinodimethane (Ag-TCNQ) and copper-tetracyanoquinodimethane (Cu-TCNQ) have been studied for data recording since they exhibit electrical bistability. 

In contrast to the reactivity of the nitroethylenes, acrylonitrile generally reacts with indoles to form the l-(2-cyanoethyl) derivatives (B-70MI30500,79MI30501), whereas Michael addition at the 3-position requires the catalytic effect of copper(II) salts. The addition-elimination reaction of pyrroles and indoles with l,l-dicyano-2-ethoxyethylene proceeds in low yield (<30%) to give the dicyanovinyl derivatives, which can be converted by standard procedures into the formyl compounds (81H(16)1499). Tetracyanoethylene forms charge transfer complexes with indoles, which collapse to the Michael adduct anions and subsequently eliminate a cyanide ion with the formation of the tricyanovinylindole (B-70MI30500). 

Dhar S, Senapati D, Das PK, Chattopadhyay P, Nethaji M, Chakravarty AR. Ternary copper complexes for photocleavage of DNA by red hght direct evidence for sulfur-to-copper charge transfer and d-d band involvement. J Am Chem Soc 2003 125 12118-24. 

At present, the accepted mechanism of 1,4-addition involves the formation of either a charge-transfer complex or an anion-radical species by partial or complete electron transfer, respectively [Eq. (92)]. Collapse of the charge-transfer complex or transfer of an organic group from the copper(II) species which results from the second process, completes the addition sequence 139). Supporting evidence for this view of the... 

Auerbach (37) recorded with a diode laser in a thin film of a solvent-coated polymer-metal ion salt complex (e.g., poly-2-vinylpyridine-AgNO3). Using short-duration pulses (120 ns) of 820-nm light (10 mW), he showed that high reflectivity marks could be created that could be read with a lower power diode laser. The mechanism is believed to involve thermally induced electron transfer from the polymer to the metal ion forming localized metal areas (Ag + e — Ag°). The concept is not limited to silver salts of gold, copper, and tellurium can be used. Polymers other than vinylpyridine that can form charge-transfer complexes with metal ions should function as electron-transfer binders. 

In most charge-transfer complexes involving a metal ion, the metal serves as the electron acceptor. Exceptions are the 1,10-phenanthroline complexes of iron(II) (Section 37N-2) and copper(I), in which the ligand is the acceptor and the metal ion the donor. A few other examples of this type of complex are known. 

A somewhat different situation is presented by the pressure effects seen in the emission spectra of the rhenium(I) complex ReBr(CO)3(phen) and the copper(I) cluster Cu4I4py4 (where py = pyridine) and related species. The former displays strong MLCT emission in ambient temperature fluid benzene [35] solutions while the latter displays a strong emission from an cluster centered (CC) excited state assigned as having mixed d-to-s metal-centered and iodide-to-copper charge-transfer character [36]. In each case, the emission is markedly dependent on the rigidity of the medium, and... 

The most efficient organic conductor material consists of co-crystals of tetracyano-Jt-quinodimethane, an electron-poor quinone analog, and tetrathia-fulvalen, an extremely potent electron donor. The crystals are green and have a conductivity of o = 1.5 x 10 Siemens cm Vat 66 K as compared to metallic copper with a a = 6 x 10 Siemens cm at 298 K. In order to obtain such high conductivity, organic charge transfer complexes must not appear as face-to-face dimers in crystals. In such cases, the acceptor takes up an electron and... 

Comparatively little work on copper batteries has been reported. The substitution of silver by copper in RbAg I does not exceed 0.34 wt % and cells of/this electrolyte with copper anodes behaved in an unstable fashion. Preliminary cell measurements have also been reported using NN dimethyl triethylene-d gj ne dibromide - cuprous bromide in conjunction with copper anodes. With charge transfer complex cathodes (Br -perylene, iodine-perylene) the cells were unstable as the halogen oxidised the CuBr (or Cul) reaction product to the Cu state. With a stable behaviour was observed. 

SCHEME 30.13 Top photo-Bergman cyclization of copper metalloenediynes via metal-ligand charge transfer complex. Bottom relative energies of copper and ligand MOs proposed to be involved in the photoelectronic Bergman cyclization of Cu(I) and Cu(II)-metalloenediynes. Adapted with permission from Benites et al. [27b]. American Chemical Society. 

---