Hexatriynyl radical

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The hexatriynyl radical, C₆H, is an organic radical molecule consisting of a chain of six carbon atoms terminated by a hydrogen. It has the structure

The unpaired electron is located at the opposite end to the hydrogen atom, as indicated. Both experimental work and computer simulations on this species was done in the early 1990s.^[1]^[2]

1 Synthesis of the radical
2 Hexatriyne anion
- 2.1 Synthesis of the anion
- 2.2 Analogous species
3 References
4 See also

[edit] Synthesis of the radical

The radical can be synthesized by photolysis. Two different examples involve

Argon gas and 1,3-butadiene in a mole ratio of 1500:1
Argon gas and acetylene in a mole ratio of 100:1

[edit] Hexatriyne anion

In 2006 the negatively charged hexatriyne anion of this molecule, C₆H⁻, was the first negatively charged ion to be discovered to exist in the interstellar medium, using the Green Bank Telescope.^[3] Negative ions were thought to be unstable in this environment due to the prevalence of ultraviolet light, which dislodges extra electrons such as this.

[edit] Synthesis of the anion

The laboratory synthesis starts from acetylene C₂H₂. The reaction takes place within a DC discharge at reduced pressure in a mixture with 15% argon. The product is observed by millimeter-wave spectroscopy.

[edit] Analogous species

The two species C₄H⁻ and C₈H⁻ have also been detected.

[edit] References

^ Doyle, T.J.; L.N. Shen, C.M.L. Rittby, and W.R.M. Graham (November 1 1991). "A C≡C stretching vibration of the C₆H (hexatriynyl) radical in Ar at 10 K". Journal of Chemical Physics 95: 6224–6228. doi:10.1063/1.461568.
^ Liu, R.; X. Zhou, P. Pulay (July 15 1992). "Ab initio study of the geometry, stretching, vibrations, and assignment of the observed frequencies of the ground state C₆H (hexatriynyl) radical". Journal of Chemical Physics 97: 1602–1605. doi:10.1063/1.463236.
^ McCarthy, M. C.; C. A. Gottlieb, H. Gupta, and P. Thaddeus (December 1 2006). "Laboratory and Astronomical Identification of the Negative Molecular Ion C₆H^-" (^{[dead link]} – ^{Scholar search}). The Astrophysical Journal 652: L141–L144. doi:10.1086/510238.