TCNQ
Encyclopedia
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
.
with malononitrile
, followed by dehydrogenation of the resulting diene with bromine
:
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.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the formula (NC)2CC6H4C(CN)2. This relative of para-quinone
1,4-Benzoquinone
1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic. Impure samples are often dark-colored due to the presence...
is an electron-acceptor that is used to prepare charge transfer salts, which are of interest in the area of molecular electronics
Molecular electronics
Molecular electronics, sometimes called moletronics, involves the study and application of molecular building blocks for the fabrication of electronic components...
.
Preparation and use
TCNQ is prepared by the condensation of 1,4-cyclohexanedione1,4-Cyclohexanedione
1,4-Cyclohexanedione is the organic compound. This tan or yellow crystalline solid is one of the three isomeric cyclohexanediones. This particular diketone is used as a building block in the synthesis of more complex molecules.-Preparation:...
with malononitrile
Malononitrile
Malononitrile, also propanedinitrile, is a nitrile, with formula CH22. Malononitrile is relatively acidic, with an pKa of 11 in water...
, followed by dehydrogenation of the resulting diene with bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
:
- 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 HBrHydrogen bromideHydrogen bromide is the diatomic molecule HBr. HBr is a gas at standard conditions. Hydrobromic acid forms upon dissolving HBr in water. Conversely, HBr can be liberated from hydrobromic acid solutions with the addition of a dehydration agent, but not by distillation. Hydrogen bromide and...
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.