Cyanophosphaethyne Explained

Cyanophosphaethyne is an unstable molecular compound with structural formula N≡C–C≡P. It can be considered as cyanogen with one nitrogen atom replaced by phosphorus. It has been made as a dilute gas. Cyanophosphaethyne has been tentatively detected in the interstellar medium.^[1] Other structural isomers, such as C≡N–C≡P (isocyanophosphapropyne), C≡C-N≡P (azaphosphadicarbon), and N≡C–P=C (isocyanophosphavinylidene), have not been observed.^[2] The molecule has linear molecular geometry (C_∞v molecular symmetry).^[3]

Production

Cyanophosphaethyne can be produced by heating cyanogen azide and phosphaethyne gases to 700 °C:^[4]

N≡C–N₃ + H–C≡P → N≡C–C≡P + HN₃

Another method is to heat anhydrous methyl cyanide with anhydrous phosphorus trichloride:^[5]

N≡C–CH₃ + PCl₃ → N≡C–C≡P + 3HCl

Properties

The dipole moment is 3.5 Debye.^[4] Having a large dipole makes the molecule easier to detect by certain types of spectroscopy than many other phosphorus containing molecules.^[4] The bond lengths are C≡N = 1.159 Å, C–C = 1.378 Å, and C≡P = 1.544 Å.^[4]

Notes and References

1. Agúndez . Marcelino . Cernicharo . José . Guélin . Michel . New molecules in IRC +10216: confirmation of C₅S and tentative identification of MgCCH, NCCP, and SiH₃CN . Astronomy & Astrophysics . 15 October 2014 . 570 . A45 . 10.1051/0004-6361/201424542. 1408.6306 . 2014A&A...570A..45A . free .
2. Pham-Tran . Nguyen-Nguyen . Hajgató . Balázs . Veszpre´mi . Tamás . Tho Nguyen . Minh . Theoretical study of cyanophosphapropyne (NCCP), isocyanophosphapropyne (CNCP) and their isomers: stability and properties . Physical Chemistry Chemical Physics . 2001 . 3 . 9 . 1588–1597 . 10.1039/b100463h. 2001PCCP....3.1588P .
3. Kwon . Ohyun . McKee . Michael L. . Theoretical Calculations on the NCCP Potential Energy Surface . The Journal of Physical Chemistry A . January 2001 . 105 . 2 . 478–483 . 10.1021/jp0031855. 2001JPCA..105..478K .
4. Cooper . Terry A. . Kroto . Harold W. . Nixon . John F. . Ohashi . Osamu. Harry Kroto . Detection of C-cyanophosphaethyne, N≡C–C≡P, by microwave spectroscopy . J. Chem. Soc., Chem. Commun. . 1980 . 8 . 333–334 . 10.1039/C39800000333.
5. Bizzocchi . Luca . Thorwirth . Sven . Müller . Holger S.P. . Lewen . Frank . Winnewisser . Gisbert . Submillimeter-Wave Spectroscopy of Phosphaalkynes: HCCCP, NCCP, HCP, and DCP . Journal of Molecular Spectroscopy . January 2001 . 205 . 1 . 110–116 . 10.1006/jmsp.2000.8234. 11148114 . 2001JMoSp.205..110B .