Cyclo (18) carbon

The correct title of this article is " Cyclo [18] carbon ". This notation is not possible in Wikipedia due to technical restrictions .

Structural formula
General
Surname	Cyclo (18) carbon
other names	1,3,5,7,9,11,13,15,17-cyclooctadecanonain
Molecular formula	C 18
Brief description	highly reactive substance with semiconductor properties
External identifiers / databases
CAS number 126487-09-0 PubChem 14940714 Wikidata Q66480924
properties
Molar mass	216.20 g mol −1
safety instructions
GHS hazard labeling no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

1,3,5,7,9,11,13,15,17-Cyclooctadecanonain or Cyclo [18] carbon is an allotropic modification of carbon with the empirical formula C ₁₈ . The molecule is a homocyclic compound , the carbon atoms are alternately linked by single and triple bonds . It therefore belongs to the polyynes and the cyclocarbons and was the first cyclocarbon ever to be isolated in 2019 at temperatures just above absolute zero .

discovery

In 1989 the existence of cyclo [18] carbon in the gas phase was demonstrated for the first time. Cyclo [18] carbon was predicted to be the smallest stable cyclocarbon and a ring strain of 72 kcal / mol was calculated. For a long time there have been different views on the structure of cyclo [18] carbon. Depending on the type of calculation, either a structure with cumulative double bonds ( cumuli ) or one with conjugated single and triple bonds (polyyne) was considered to be more stable. In either case, all atoms are sp hybridized .

In 2019, researchers from IBM and the University of Oxford announced that they were able to isolate the substance on a solid phase and characterize the molecular structure. The synthesis was achieved by the electrochemical cleavage of six carbon monoxide molecules from one molecule of the molecular formula C ₂₄ O ₆ at –268 ° C:

.

The structure elucidation clearly demonstrated that cyclo [18] carbon has conjugated single and triple bonds and not, as was previously assumed, only cumulative C = C double bonds.

properties

The connection is very reactive. Initial studies suggest that it has semiconductor properties. In addition, it is assumed that it exhibits non-linear optical effects .

outlook

The researchers hope that the reactivity of the compound will enable them to produce other carbon allotropes, especially fullerenes , or other carbon-rich compounds. In addition, the synthesis is seen as a step on the way to the production of transistors in the field of molecular electronics.

Individual evidence

1. ↑ ^{a b c d e f g h} Katharina Kaiser, Lorel M. Scriven, Fabian Schulz, Przemyslaw Gawel, Leo Gross, Harry L. Anderson: An sp-hybridized molecular carbon allotrope, cyclo [18] carbon . In: Science . 2019, p. eaay1914 , doi : 10.1126 / science.aay1914 .
2. ↑ ^{a b c} Davide Castelvecchi: Chemists make first-ever ring of pure carbon . In: Nature . tape 572 , no. 7770 , August 2019, p. 426 , doi : 10.1038 / d41586-019-02473-z .
3. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
4. ^ ^{A b} François Diederich , Yves Rubin, Carolyn B. Knobler, Robert L. Whetten, Kenneth E. Schriver, Kendall N. Houk, Yi Li: All-Carbon Molecules: Evidence for the Generation of Cyclo [18] carbon from a stable Organic precursor . In: Science . tape 245 , no. 4922 , 1989, pp. 1088-1090 , doi : 10.1126 / science.245.4922.1088 .
5. ↑ ^{a b c} George A. Adamson and Charles W. Rees: Towards the total synthesis of cyclo [n] carbons and the generation of cyclo [6] carbon . In: Journal of the Chemical Society, Perkin Transactions 1 . No. 13 , 1996, pp. 1535-1543 , doi : 10.1039 / P19960001535 .