Carbyne

Carbyne

In chemistry, a carbyne is a monovalent carbon radical species. It occurs in several ways.

Gas phase

A carbyne can occur as a short-lived reactive intermediate. For instance, fluoromethylidyne (CF) can be detected in the gas phase by spectroscopy as an intermediate in the flash photolysis of CHFBr2. [Chemistry of carbynes: reaction of CF, CCl, and CBr with alkenes B. P. Ruzsicska, A. Jodhan, H. K. J. Choi, O. P. Strausz, T. N. Bell; "J. Am. Chem. Soc."; 1983; 105(8); 2489-2490.]

Organometallic

Carbynes are incorporated in metal carbyne complexes. [http://www.u-bourgogne.fr/EuroH-2000/furno.pdf] [Details of their reactivity and that of the related carbenes is shown at http://www.thieme-chemistry.com/thieme-chemistry/sos/info/include/pdf/sc02.pdf.] For example, in Unicode| [WBr(CO)2(2,2'-bipyridine)C-Aryl] and Unicode| [WBr(CO)2(PPh3)2C-NR2] . An example of how to make such a compound would be to react Unicode| [(CO)6] with Lithium diisopropylamide to form [(iPr2N)(OLi)C=W(CO)5] . This is then reacted with either oxalyl bromide or Br-Br-PPh3 followed by triphenyl phosphine. Another method is to treat a methoxy metal carbene with a lewis acid. [http://pubs.rsc.org/ej/CC/2000/b002228o.pdf]

Form of carbon

Carbyne, or polyyne, is also another name for Linear Acetylenic Carbon [Dangerously Seeking Linear Carbon, Ray H. Baughman, "Science" 19 May 2006: Vol. 312. no. 5776, pp. 1009-1110.] (LAC), the carbon allotrope that has the chemical structure [Carbyne and Carbynoid Structures Series: Physics and Chemistry of Materials with Low-Dimensional Structures, Vol. 21 Heimann, R.B.; Evsyukov, S.E.; Kavan, L. (Eds.) 1999, p.452, Hardcover ISBN 0-7923-5323-4] -(C:::C)n- . Carbon in this modification is linear with "sp" orbital hybridisation, and is a polymer with alternating single and triple bonds. This type of carbyne is of considerable interest to nanotechnology as its Young's modulus is forty times that of the hardest known material — diamond. [Harder than Diamond: Determining the Cross-Sectional Area and Young's Modulus of Molecular Rods, Lior Itzhaki et al, "Angew. Chem. Int. Ed." 2005, 44, 7432-7435.]

References

ee also

*http://www.sciencemag.org/cgi/content/abstract/267/5196/362
* [http://books.google.com/books?id=9llD6IFVvfgC&pg=PA387&lpg=PA387&dq=carbon+allotrope&source=web&ots=MNb3UT08sE&sig=fjneO9szE15jHiKuSsWu4WW6KHA#PPA420,M1 Acetylene Chemistry]
* [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFN-4BM8JR1-1&_user=1010281&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050264&_version=1&_urlVersion=0&_userid=1010281&md5=207d8a67411db7a448a634eb898fa418 Linear carbon allotrope – carbon atom wires prepared by pyrolysis of starch ]
* [http://www.sciencemag.org/cgi/rapidpdf/267/5196/362.pdf Synthesis of LAC - "the sp carbon allotrope"]


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