Pentalene
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| Names | |
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| IUPAC name
Pentalene
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| Identifiers | |
250-25-9  |
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| ChEBI | CHEBI:33074 |
| ChemSpider | 4574194  |
| Jmol 3D model | Interactive image |
| PubChem | 5460726 |
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| Properties | |
| C8H6 | |
| Molar mass | 102.14 g·mol−1 |
| Vapor pressure | {{{value}}} |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Pentalene is a polycyclic hydrocarbon composed of two fused cyclopentadiene rings.[1] It has chemical formula C8H6. It is antiaromatic, because it has 4n π electrons where n is any integer. For this reason it dimerizes even at temperatures as low as -100 °C.[2][3] The derivative 1,3,5-tri-tert-butylpentalene was synthesized in 1973.[4] Because of the tert-butyl substituents this compound is thermally stable. Pentalenes can also be stabilized by benzannulation for example in the compounds benzopentalene and dibenzopentalene.[1]
Dilithium pentalenide was isolated in 1962, long before pentalene itself in 1997.[5] 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 10π-electron 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.[6]
See also
References
- ↑ 1.0 1.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
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- ↑ Hafner, K. and Süss, H. U. (1973), 1,3,5-Tri-tert-Butylpentalene. A Stabilized Planar 8π-Electron System. Angew. Chem. Int. Ed. Engl., 12: 575–577. doi:10.1002/anie.197305751
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
