- Hexatriynyl radical
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. [cite journal| journal=
Journal of Chemical Physics | volume=95| pages=6224–6228| year= 1991| month= November 1| title=A C≡C stretching vibration of the C6H (hexatriynyl) radical in Ar at 10 K| first=T.J.| last=Doyle| coauthors= L.N. Shen, C.M.L. Rittby, and W.R.M. Graham| url=| accessdate=2006-12-05|doi = 10.1063/1.461568] [cite journal| journal=Journal of Chemical Physics | volume=97| pages=1602–1605| year= 1992| month= July 15| title="Ab initio" study of the geometry, stretching, vibrations, and assignment of the observed frequencies of the ground state C6H (hexatriynyl) radical| first=R.| last=Liu| coauthors= X. Zhou, P. Pulay| url=| accessdate=2006-12-05 |doi=10.1063/1.463236 ]Synthesis of the radical
The radical can be synthesized by
photolysis . Two different examples involve
* Argon gas and1,3-butadiene in a mole ratio of 1500:1
* Argon gas andacetylene in a mole ratio of 100:1Hexatriyne anion
In
2006 the negatively charged hexatriyne anion of this molecule, C6H−, was the first negatively charged ion to be discovered to exist in theinterstellar medium , using theGreen Bank Telescope . [cite journal| journal=The Astrophysical Journal| volume=652| pages=L141–L144| year= 2006| month= December 1| title=Laboratory and Astronomical Identification of the Negative Molecular Ion C6H-| first=M. C. | last=McCarthy| coauthors= C. A. Gottlieb, H. Gupta, and P. Thaddeus| url=http://www.journals.uchicago.edu/doi/abs/10.1086/510238| accessdate=2006-12-05| doi=10.1086/510238| format=Abstract] Negative ions were thought to be unstable in this environment due to the prevalence ofultraviolet light , which dislodges extra electrons such as this.ynthesis 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.Analogous species
The two species C4H− and C8H− have also been detected.
References
ee also
*
Diacetylene
*Acetylene
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