7,7,8-Tetracyano-p-quinodimethane

Electron mediators successfully used with oxidases include 2,6-dichlorophenolindophol, hexacyanoferrate-(III), tetrathiafulvalene, tetracyano-p-quinodimethane, various quinones and ferrocene derivatices. From Marcus theory it is evident that for long-range electron transfer the reorganization energies of the redox compound have to be low. Additionally, the redox potential of the mediator should be about 0 to 100 mV vs. standard calomel electrode (SCE) for a flavoprotein (formal potential of glucose oxidase is about -450 mV vs SCE) in order to attain rapid vectrial electron transfer from the active site of the enzyme to the oxidized form of the redox species. 

Tetracyano ligands have been used to bridge between four Ru(NH3)5 moieties. The complexes [ Ru(NH3)5 4(/i-L)] + (L = tetracyanoethene, tetracyano-p-quinodimethane, 1,2,4,5-tetracyano-benzene, 2,3,5,6-tetracyanopyrazine) exhibit intense, long-wavelength electronic absorptions. Oxidation to [ Ru(NH3)5 4(yU-L)] °" " and reduction to [ Ru(NH3)5 4(//-L)] + and [ Ru(NH3)5 4-(/i-L)] + can readily be achieved. The species are fully delocalized with partially reduced ligands or partially oxidized Ru centers. Treatment of [5,10,15,20-tetrakis(4-cyanophenyl)porphyrinato] cobalt(II) or [5,10,15,20-tetrakis(4-cyano-2,6,-dimethylphenyl)porphyrinato]cobalt(II) with [Ru-(NH3)5(0S02CF3)] introduces cyano-bound pendant Ru (NH3)5 groups to the porphyrinato complexes. ... 

Photoinduced oxidation of Cjq has been achieved by electron transfer from excited to a strong electron acceptor such as p-chloranil [72, 73], p-benzoquinone [73], tetracyano-p-quinodimethane (TCNQ) or tetracyanoethylene (TONE). This electron transfer proceeds efficiently only by addition of promoters such as Sc(OTf)3 or triflic acid, both of which strongly enhance the electron-transfer process [72, 73]. Another possibility to produce the cation is the electron transfer from to the singlet excited state of a strong electron acceptor such as N-methylacridinium hexafluorophosphate (NMA ) [74, 75], triphenylpyriliumtetrafluoroborate (TPP" )... 

Chemical oxidation of the TTF groups in compounds 34 and 35 has been achieved by reaction with an excess of iodine in dichloromethane solution, leading to new low-energy absorptions in the UV/visible spectra which are diagnostic of TTF cation radicals the broad absorption at = 830 nm for the iodide salt of 35 suggests the formation of aggregated TTF species. A charge transfer complex formed by 35 and tetracyano-p-quinodimethane (TCNQ) has been isolated as an insoluble black powder. The stoichiometry is (35), (TCNQ)3 (i.e. 8 TTF units 3... 

Since the discovery in 1973 of metal-like conductivity in the charge transfer salt tetrathiafulvalene-tetracyano-p-quinodimethane (TTF-TCNQ, 1,-2), a host of new materials have been prepared displaying this interesting property. Widespread research on these materials has led to an improved understanding of the physics underlying the organic metallic state, and to a succession of molecular modifications which have enhanced these properties. ... 

Bulk crystalline radical ion salts and electron donor-electron acceptor charge transfer complexes have been shown to have room temperature d.c. conductivities up to 500 Scm-1 [457, 720, 721]. Tetrathiafiilvalene (TTF), tetraselenoful-valene (TST), and bis-ethyldithiotetrathiafulvalene (BEDT-TTF) have been the most commonly used electron donors, while tetracyano p-quinodimethane (TCNQ) and nickel 4,5-dimercapto-l,3-dithiol-2-thione Ni(dmit)2 have been the most commonly utilized electron acceptors (see Table 8). Metallic behavior in charge transfer complexes is believed to originate in the facile electron movements in the partially filled bands and in the interaction of the electrons with the vibrations of the atomic lattice (phonons). Lowering the temperature causes fewer lattice vibrations and increases the intermolecular orbital overlap and, hence, the conductivity. The good correlation obtained between the position of the maximum of the charge transfer absorption band (proportional to... 

Values are for the 1 1 complex of 1,10-phenanthroline with 7,7,8,8-tetracyano-p-quinodimethane. 

There has been some interest in the electrical conductivity and magnetic properties of salts of 1,10-phenanthroline and 1-alkyl-1,10-phenanthrolinium cations with 7,7,8,8-tetracyano-p-quinodimethane and its anion radical297-302 and related species.303... 

Charge transfer complexes between various phenanthrolines and tetracyano-p-quinodimethane have been patented as inks and copying materials because of their high color.300... 

The tetrabutylammonium salts of the bis chelates are semiconductors but exhibit enhanced conducting properties after doping with iodine. The corresponding salts which are formed when Bi N is replaced by TTF+ or TSeF+ have higher conductivities than the analogous dithiolene complexes with magnitudes similar to that of TTF-TCNQ (TTF = tetrathiafulvalene, TSeF = tetraselenofulvalene, TCNQ = tetracyano-p-quinodimethane). 

Earlier, I criticized the Cooper pair being philosophically unacceptable because the proposed pair is not seen elsewhere outside of the BCS superconductivity theory. The same measurement must be placed against the Covalon-Conduction theory proposed here. We shall show therefore, that a number of physical property changes observed in [TCNQ-TTF] (tetracyano-p-quinodimethane-tetrathiofulvalene), an organic compound, as a function of temperature can be interpreted and understood in terms of Covalon-conduction . 

Other functional polymers were prepared for which the counteranions (BF4, PF6-,. ..) were replaced by the tetracyano-p-quinodimethane radical... 

Diorgano telluriums form donor-acceptor complexes with 1,4-dinitrobenzene, tetrachloro-p-benzoquinone, and 7,7,8,8-tetracyano-p-quinodimethane. These adducts are formed when the components are refluxed in acetonitrile or acetone. The following adducts were prepared ... 

Salts Derived from 7,7,8,8-Tetracyano-p-quinodimethane (TCNQ, 41)... 

Abbreviations ave, average cot, cyclooctatetraene Cp, tT -cyclopentadienyl DME, 1,2-dimethoxyetbane DMF, A, iV-dimethylformamide dppe, Ph2PCH2CH2PPIi2 ESR, electron spin resonance Fc, ferrocenyl HOMO, highest occupied molecular orbital LUMO, lowest unoccupied molecular orbital see, saturated calomel electrode TCNQ, 7,7,8,8-tetracyano-p-quinodimethane THF, tetrahydrofiiran. 

An X-ray crystal structure of 9-methoxy-ll-demethylellipticine (9) (25) reveals little difference in geometry from that previously observed in ellipticine and its derivatives (29,30). Thus, the absence of a methyl group at C-11 and the presence of the 9-methoxyl substituent does not alter the pyrido[4,3-5]carbazole structure. An X-ray crystal structure study of the charge-transfer complex formed between 9-methoxyellipticine (2) and 7,7,8,8-tetracyano-p-quinodimethane... 

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