Tetracyanomethane - Misplaced Pages

Tetracyanomethane
Names


Preferred IUPAC name Methanetetracarbonitrile
Other names carbon tetracyanide; 2,2-dicyanomalononitrile
Identifiers
CAS Number	24331-09-7
3D model (JSmol)	Interactive image
ChemSpider	124462
PubChem CID	141101
UNII	K559RM8NV6
CompTox Dashboard (EPA)	DTXSID70179070
InChI InChI=1S/C5N4/c6-1-5(2-7,3-8)4-9Key: XKGUKYPCHPHAJL-UHFFFAOYSA-N
SMILES C(#N)C(C#N)(C#N)C#N
Properties
Chemical formula	C(CN)₄
Molar mass	116.083 g·mol
Appearance	white crystals
Structure
Crystal structure	trigonal
Space group	R3c
Lattice constant	a = 9.062, c = 11.625
Lattice volume (V)	137.8 Å
Formula units (Z)	6
Molecular shape	tetrahedron
Thermochemistry
Std enthalpy of formation (Δ_fH₂₉₈)	−146.2 kcal/mol
Heat of combustion, higher value (HHV)	−616.4 kcal/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references

Chemical compound

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.

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. The molecules of tetracyanomethane have a tetrahedral symmetry (43m or T_d). 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. The C-C bond has a force constant of 4.86×10 dyn/cm which is slightly greater than the C-Cl bond in carbon tetrachloride, but a fair bit weaker than in the tricyanomethanide ion. At pressures over 7 GPa tetracyanomethane starts to polymerize to form a disorganised covalent network solid. At higher pressure the white colour yellows and darkens to black. Over 20 GPa the polymerization is total.

The bulk modulus K₀ = 4.4 and its derivative K₀' = 18.

Production

Tetracyanomethane can be made by reacting cyanogen chloride with silver tricyanomethanide.

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.

References

^ 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.
^ Mayer, Erwin (1969). "Darstellung und Eigenschaften von Tetracyanmethan". Monatshefte für Chemie. 100 (2): 462–468. doi:10.1007/BF00904089. S2CID 92450428.
^ 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.
^ 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.
^ 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.