Tetracyanoquinodimethane

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Tetracyanoquinodimethane (TCNQ)
Other names

(2,5-Cyclohexadiene-1,4-diylidene)
-dimalononitrile, 7,7,8,8-Tetracyanoquinodimethane

Identifiers
CAS number 1518-16-7 YesY
PubChem 73697
ChemSpider 66342 YesY
ChEBI CHEBI:52445 YesY
Jmol-3D images Image 1
Properties
Molecular formula C12H4N4
Molar mass 204.19 g/mol
Appearance green-coloured crystals
Melting point 293.5–296 °C
Boiling point sublimes
Hazards
EU classification not listed
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Tetracyanoquinodimethane (TCNQ) is the organic compound with the formula (NC)2CC6H4C(CN)2. This relative of para-quinone is an electron-acceptor that is used to prepare charge transfer salts, which are of interest in the area of molecular electronics. It is also an important cyanocarbon.

Preparation and use

TCNQ is prepared by the condensation of 1,4-cyclohexanedione with malononitrile, followed by dehydrogenation of the resulting diene with bromine:[1]

C6H8O2 + 2 CH2(CN)2 → C6H8(C(CN)2)2 + 2 H2O
C6H8(C(CN)2)2 + 2 Br2 → C6H4(C(CN)2)2 + 4 HBr

Like TCNE, TCNQ is easily reduced electrochemically to give a blue-coloured radical anion. Upon treatment with the electron donor tetrathiafulvene (TTF), it forms an ion-pair (TTF-TCNQ complex) where the TCNQ is the acceptor. This salt crystallizes as a one-dimensional polymer, consisting of segregated stacks of cations and anions of the donors and the acceptors, respectively.

References

  1. ↑ "Substituted Quinodimethans. I. Preparation and Chemistry of 7,7,8,8-Tetracyanoquinodimethan" J. Am. Chem. Soc. 1962, Volume 84, pp. 3370-3374. doi:10.1021/ja00876a028
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