Pentalene
From Wikipedia, the free encyclopedia
| Pentalene | |
|---|---|
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.png/140px-Pentalene_(structure).png) |
| IUPAC name | Pentalene |
| Identifiers | |
| CAS number | [250-25-9] |
| PubChem | |
| ChEBI | |
| SMILES | c1cc2cccc2c1 |
| InChI | 1/C8H6/c1-3-7-5-2-6-8(7)4-1/h1-6H |
| Properties | |
| Molecular formula | C8H6 |
| Molar mass | 102.13 g/mol |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Pentalene is a polycyclic hydrocarbon composed of two fused cyclopentadiene rings. It has chemical formula C8H6. It is antiaromatic, because it has 4n pi electrons. For this reason it dimerizes even at temperatures as low as -100°C [1] [2]
Dilithium pentalenide was isolated (1962) long before pentalene itself (1997) [3] It is prepared from reaction of dihydropentalene (pyrolysis of an isomer of dicyclopentadiene) with n-butyllithium in solution and forms a stable salt. In accordance with its structure proton NMR shows 2 signals in a 2 to 1 ratio. The addition of two electrons removes the antiaromaticity; it becomes a planar 10 pi aromatic species and is thus a bicyclic analogue of the cyclooctatetraene (COT) dianion C8H82-.
The dianion can also be considered as two fused cyclopentadienyl rings, and has been used as a ligand in organometallic chemistry to stabilise many types of mono- and bimetallic complexes, including those containing multiple metal-metal bonds, and anti-bimetallics with extremely high levels of electronic communication between the centers [4]
[edit] See also
[edit] References
- ^ Carey, Francis A.; Sundberg, Richard J.; (1984). Advanced Organic Chemistry Part A Structure and Mechanisms (2nd ed.). New York N.Y.: Plenum Press. ISBN 0-306-41198-9.
- ^ Bally T., Chai S., Neuenschwander M., Zhu Z. (1997). "Pentalene: Formation, Electronic, and Vibrational Structure" (reprint). J. Am. Chem. Soc. 119: 1869-1875(7). doi:.
- ^ The Pentalenyl Dianion Thomas J. Katz, Michael Rosenberger J. Am. Chem. Soc.; 1962; 84(5); 865-866. doi:10.1021/ja00864a038
- ^ The Organometallic Chemistry of Pentalene Owen T. Summerscales, F. Geoffrey N. Cloke Coord. Chem. Rev.; 2006; 250; 1122-1140.
