Tetracyanomethane
Chemical compound From Wikipedia, the free encyclopedia
Tetracyanomethane or carbon tetracyanide is an organic compound with the chemical formula C(CN)4. It is a percyanoalkane. It is a molecular carbon nitride. The structure can be considered as methane with all hydrogen atoms replaced by cyanide groups. It was first made by Erwin Mayer in 1969.[2][3]
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| Names | |
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| Preferred IUPAC name
Methanetetracarbonitrile | |
| Other names
carbon tetracyanide; 2,2-dicyanomalononitrile | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C(CN)4 | |
| Molar mass | 116.083 g·mol−1 |
| Appearance | white crystals |
| Structure | |
| trigonal | |
| R3c | |
a = 9.062, c = 11.625 | |
Lattice volume (V) |
137.8 Å3 |
Formula units (Z) |
6 |
| tetrahedron | |
| Thermochemistry[1] | |
Std enthalpy of formation (ΔfH⦵298) |
−146.2 kcal/mol |
| −616.4 kcal/mol | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Properties
Tetracyanomethane is a solid at room temperature. It decomposes over 160 °C without melting, and although it can be in a dilute vapour, no liquid form is known.[2] The molecules of tetracyanomethane have a tetrahedral symmetry (43m or Td). The molecule has C-C distance of 1.484 Å and C-N distance of 1.161 Å in the gas form. In the solid the C≡N bond shortens to 1.147 Å.[3] The C-C bond has a force constant of 4.86×105 dyn/cm which is slightly greater than the C-Cl bond in carbon tetrachloride, but a fair bit weaker than in the tricyanomethanide ion.[4] At pressures over 7 GPa tetracyanomethane starts to polymerize to form a disorganised covalent network solid. At higher pressure the white colour[1] yellows and darkens to black. Over 20 GPa the polymerization is total.[5]
The bulk modulus K0 = 4.4 and its derivative K0' = 18.[5]
Production
Tetracyanomethane can be made by reacting cyanogen chloride with silver tricyanomethanide.[4]
- ClCN + AgC(CN)3 → C(CN)4 + AgCl
Reactions
In an acid solution in water tetracyanomethane is hydrolysed to yield tricyanomethanide and ammonium ions along with carbon dioxide. In alkaline solutions tricyanomethanide and cyanate ions are produced.[4]
See also
- Tricyanomethane (cyanoform)
- Tetraethynylmethane
References
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