Tetracyanoquinodimethane

Tetracyanoquinodimethane (TCNQ)
Other names

(2,5-Cyclohexadiene-1,4-diylidene)
-dimalononitrile, 7,7,8,8-Tetracyanoquinodimethane
Identifiers
CAS number 1518-16-7 Y
PubChem 73697
ChemSpider 66342 Y
ChEBI CHEBI:52445 Y
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
 Y (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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.

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 the “organic metal” TTF-TCNQ 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