Tetracyanomethane

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Tetracyanomethane
Tetracyanomethane.svg
Tetracyanomethane-from-xtal-3D-bs-17.png
Names
Preferred IUPAC name
Methanetetracarbonitrile
Other names
carbon tetracyanide; 2,2-dicyanomalononitrile
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/C5N4/c6-1-5(2-7,3-8)4-9
    Key: XKGUKYPCHPHAJL-UHFFFAOYSA-N
  • C(#N)C(C#N)(C#N)C#N
Properties
C(CN)4
Molar mass 116.083 g·mol−1
Appearancewhite crystals
Structure
trigonal
R3c
a = 9.062, c = 11.625
137.8 Å3
6
tetrahedron
Thermochemistry [1]
−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).

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]

Contents

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

References

  1. 1 2 Barnes, D.S.; Mortimer, C.T.; Mayer, E. (July 1973). "The enthalpy of formation of tetracyanomethane". The Journal of Chemical Thermodynamics. 5 (4): 481–483. Bibcode:1973JChTh...5..481B. doi:10.1016/S0021-9614(73)80095-3.
  2. 1 2 Mayer, Erwin (1969). "Darstellung und Eigenschaften von Tetracyanmethan". Monatshefte für Chemie. 100 (2): 462–468. doi:10.1007/BF00904089. S2CID   92450428.
  3. 1 2 Britton, D. (1 July 1974). "The crystal structure of tetracyanomethane, C(CN)4". Acta Crystallographica Section B. 30 (7): 1818–1821. Bibcode:1974AcCrB..30.1818B. doi:10.1107/S0567740874005863.
  4. 1 2 3 Hester, Ronald E.; Lee, Kenneth Michael; Mayer, Erwin (September 1970). "Tetracyanomethane as a pseudo-(carbon tetrahalide)". The Journal of Physical Chemistry. 74 (18): 3373–3376. doi:10.1021/j100712a011.
  5. 1 2 Keefer, Derek W.; Gou, Huiyang; Wang, Qianqian; Purdy, Andrew; Epshteyn, Albert; Juhl, Stephen J.; Cody, George D.; Badding, John; Strobel, Timothy A. (12 February 2018). "Tetracyanomethane under Pressure: Extended CN Polymers from Precursors with Built-in sp3 Centers". The Journal of Physical Chemistry A. 122 (11): 2858–2863. Bibcode:2018JPCA..122.2858K. doi:10.1021/acs.jpca.7b10729. OSTI   1430339. PMID   29432685.
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