Conductive charge transfer solids

TCNE ( ° = -0.27 and -1.27 V relative to PeCp2 in MeCN) and TCNQ E° = -0.30 V and -0.88 V relative to PeCp2 in MeCN) are commercially available mild one-electron acceptors which have attracted, as such, a considerable interest for the construction of low-dimensional organic and organometallic charge-transfer solids with magnetic [277] and conducting properties [278]. For instance, the salt... 

Metallic conductivity, superconductivity, and cooperative magnetic properties are the most significant attributes of these donor-acceptor (and partial charge transfer) solids." These properties derive from the partially occupied delocalized n-orbitals of the donor and acceptor species, which overlap to form energy bands along the stacks. Interactions between the stacks are less important, as the conductivities are usually anisotropic. Enlargement of the donor and acceptor species diminishes the coulombic destabilization of stacks of homo-(partially)-charged molecules. 

Dimethyl a,a,a, a -tetracyano-2,5-diisopropyl-l,4-phenylenediacetate added at 70° to aq. 5%-KOH, stirred 1 min. until a soln. results, carefully acidified with 6 N HCl, and the solid treated with a slight excess of bromine water 2,5-diiso-propyl-7,7,8,8-tetracyanoquinodimethane. Y 86%. F. e. s. R. C. Wheland and E. L. Martin, J. Org. Chem. 40, 3101 (1975) electrically conductive charge transfer complexes with quinodimethanes and heteroethylenes such as heterofulvalenes s. Am. Soc. 98, 3916 (1976) comparison of 1,1-dinitrile with oxygen groups, review, s. K. Wallenfels et al., Ang. Ch. 88, 311 (1976) reactions of 7,7,8,8-tetracyano-quinodimethane, review, s. B. P. Bespalov and V. V. Titov, Russ. Chem. Rev. 44, 1091 (1975) (Engl, transl.). 

M.p. 296 C. Accepts an electron from suitable donors forming a radical anion. Used for colorimetric determination of free radical precursors, replacement of Mn02 in aluminium solid electrolytic capacitors, construction of heat-sensitive resistors and ion-specific electrodes and for inducing radical polymerizations. The charge transfer complexes it forms with certain donors behave electrically like metals with anisotropic conductivity. Like tetracyanoethylene it belongs to a class of compounds called rr-acids. tetracyclines An important group of antibiotics isolated from Streptomyces spp., having structures based on a naphthacene skeleton. Tetracycline, the parent compound, has the structure ... 

Though solid electrolytes for multivalent ions offer the advantage of a larger charge transfer, their conductivities are much lower than those of monovalent ions at ambient temperature because of a higher activation enthalpy for the ionic motion... 

Solid State Properties. Perhaps as a result of the limited intermolecular interactions of these complexes in the solid state, they exhibit few solid-state properties of interest. The dianionic 7a did successfully produce a charge transfer material by mixing it with a solution of the tetrathiafulvalene-based salt (TTF)3(BF4)2. Elemental analysis of the resulting black product gave the formula (TTF)4[7a]3 and the material exhibited a conductivity of 9 x 10 S... 

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