Tetracyanoquinodimethane

Tetracyanoquinodimethane (TCNQ)

AFM image of fluorinated TCNQ on graphene
Names
Other names (2,5-Cyclohexadiene-1,4-diylidene) -dimalononitrile, 7,7,8,8-Tetracyanoquinodimethane
Identifiers
CAS Number	1518-16-7 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:52445 Y
ChemSpider	66342 Y
ECHA InfoCard	100.014.704
PubChem CID	73697
InChI InChI=1S/C12H4N4/c13-5-11(6-14)9-1-2-10(4-3-9)12(7-15)8-16/h1-4H Y Key: PCCVSPMFGIFTHU-UHFFFAOYSA-N Y InChI=1S/C12H4N4/c13-5-11(6-14)9-1-2-10(4-3-9)12(7-15)8-16/h1-4H
SMILES c1cc(=C(C#N)C#N)ccc1=C(C#N)C#N
Properties
Chemical formula	C12H4N4
Molar mass	204.19 g/mol
Appearance	green colored powder or orange crystals
Melting point	293.5 to 296 °C (560.3 to 564.8 °F; 566.6 to 569.1 K)
Boiling point	sublimes
Hazards
EU classification (DSD) (outdated)	not listed
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

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

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

The molecule is planar, with D_2hsymmetry.

Like tetracyanoethylene (TCNE), TCNQ is easily reduced to give a blue-coloured radical anion. The reduction potential is about −0.3 V relative to the ferrocene/ferrocenium couple. This property is exploited in the development of charge transfer salts. TCNQ also forms complexes with electron-rich metal complexes.

TCNQ achieved great attention because it forms charge-transfer salts with high electrical conductivity. These discoveries were influential in the development of organic electronics. Illustrative is the product from treatment of TCNQ with the electron donor tetrathiafulvene (TTF), TCNQ forms an ion pair, the TTF-TCNQ complex, in which TCNQ is the acceptor. This salt crystallizes in a one-dimensionally stacked polymer, consisting of segregated stacks of cations and anions of the donors and the acceptors, respectively. The complex crystal is an organic semiconductor that exhibits metallic electric conductivity.