Tetracyanoquinodimethane metal salts

Polymers from tetracyanotetrathiafulvalen and metal salts exhibit 029 of 10 to 10 ohm cm . Doping with tetracyanoquinodimethane has no influence on a. This is surprising because doping of tetrathiafulvalene leads to the well known metallic conductivity. 

J. B. Torrance, The difference between metallic and insulating salts of tetracyanoquinodimethane (TCNQ) How to design an organic metal, Acc. Chem. Res. 12 79-86 (1979). 

Tetracyanoquinodimethane (TCNQ) and many of its derivatives are easily reduced to anions of the type TCNQ-, which form salts with various cations. With many cations, e.g., tetrathiafulvalene cations (TTF+), and N-methyl phenazinium cations (NMP+), the TCNQ- anions form electronically conducting salts (- molecular metals, -> charge-transfer complexes) that can be used as electrodes, especially because of their electrocatalytic properties (- biosensors, -> electrocatalysis, -> molecular metals) [i,ii]. TCNQ undergoes insertion electrochemical reactions (-> insertion electrochemistry) leading to TCNQ salts [iii, iv]. Polymers... 

Tetrathiafulvalene electrodes — Tetrathiafulvalene (TTF) and many of its derivatives are easily oxidized to form cations of the type TTF+. With various anions, most prominent is the tetracyanoquinodimethane anion (TCNQ-), these cations form - charge-transfer complexes, i.e., salts with metal-like conductivities (- molecular metals). These salts are used in electrochemistry as electrodes or to modify the surface of electrodes, for the purpose of achieving desirable electrocatalytic properties (- electrocatalysis). Tetrathiafulvalene-substituted polystyrenes have also been synthesized and used as modified electrodes [ii]. 

Well-known donor and acceptor molecules are tetrathi-afulvalene (TTF) and tetracyanoquinodimethane (TCNQ), respectively. A 1 1 TCNQ TTF salt exhibits a high room-temperature conductivity (5 x lO S m ) and metallic behavior is observed as the temperature is reduced to 54 K (i.e., the conductivity increases with decreasing temperature). The molecules in such compounds are arranged in segregated stacks, in which donors and acceptors form separate donor stacks (DDDDDD...) and acceptor stacks... 

The tetrathiafulvalenes are of interest because of their ability to form charge-transfer salts with metallic properties. Thus (4) forms a charge-transfer salt with tetracyanoquinodimethane. 

The discovery that the charge-transfer salt derived from tetrathiafulvalene (54 R = H) and tetracyanoquinodimethane (55) has metal-like behaviour, and shows a remarkable electrical conductivity over a wide temperature range, has stimulated a large volume of work on the design and synthesis of organic metals . ... 

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