Fulvalene (bicyclopentadienylidene) is the member of the fulvalene family with the molecular formula C10H8. It is of theoretical interest as one of the simplest non-benzenoid conjugated hydrocarbons. Fulvalene is an unstable isomer of the more common benzenoid aromatic compounds naphthalene and azulene. Fulvalene consists of two 5-membered rings, each with two double bonds, joined by yet a fifth double bond. It has D2h symmetry.
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| Names | |
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| Preferred IUPAC name
[1,1′-Bi(cyclopentylidene)]-2,2′,4,4′-tetraene | |
| Other names
Bicyclopentyliden-2,4,2′,4′-tetraene
1,1′-Bi[cyclopentadienylidene] Pentafulvalene Bicyclopentadienylidene [5,5′]Bicyclopentadienylidene | |
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C10H8 | |
| Molar mass | 128.174 g·mol−1 |
| Density | 1.129 g/ml |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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History
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An earlier attempt at synthesis of fulvalene in 1951 by Pauson and Kealy resulted in the accidental discovery of ferrocene.[1] Its synthesis was first reported in 1958 by E. A. Matzner, working under William von Eggers Doering.[2] In this method, the cyclopentadienyl anion is coupled with iodine to the dihydrofulvalene. Double deprotonation of the dihydrofulvalene with n-butyllithium gives the dilithio derivative, which is oxidized by oxygen. Fulvalene was spectroscopically observed at −196 °C (77 K) from photolysis of diazocyclopentadiene, which induces dimerization of cyclopentadiene-derived carbenes.[3] The compound was isolated in 1986[4] and was found to be nonaromatic. Above −50 °C (223 K) it dimerizes by a Diels–Alder reaction.
Derivatives
editPerchlorofulvalene (C4Cl4C)2 is quite stable in contrast to fulvalene itself.[5]
See also
edit- Fulvenes, (CH=CH)2C=CH2 and substituted derivatives
- Tetrathiafulvalene, C2H2S2C=CS2C2H2
References
edit- ^ T. J. Kealy, P. L. Pauson (1951). "A New Type of Organo-Iron Compound". Nature. 168 (4285): 1039–1040. Bibcode:1951Natur.168.1039K. doi:10.1038/1681039b0. S2CID 4181383.1039-1040&rft.date=1951&rft_id=https://api.semanticscholar.org/CorpusID:4181383#id-name=S2CID&rft_id=info:doi/10.1038/1681039b0&rft_id=info:bibcode/1951Natur.168.1039K&rft.au=T. J. Kealy, P. L. Pauson&rfr_id=info:sid/en.wikipedia.org:Fulvalene" class="Z3988">
- ^ Dissertation Abstracts Int'l 26-06 page 3270 6411876.
- ^ Demore, William B.; Pritchard, H. O.; Davidson, Norman (1959). "Photochemical Experiments in Rigid Media at Low Temperatures. II. The Reactions of Methylene, Cyclopentadienylene and Diphenylmethylene". Journal of the American Chemical Society. 81 (22): 5874–5879. doi:10.1021/ja01531a008.5874-5879&rft.date=1959&rft_id=info:doi/10.1021/ja01531a008&rft.aulast=Demore&rft.aufirst=William B.&rft.au=Pritchard, H. O.&rft.au=Davidson, Norman&rfr_id=info:sid/en.wikipedia.org:Fulvalene" class="Z3988">
- ^ Escher, André; Rutsch, Werner; Neuenschwander, Markus (1986). "Synthese von Pentafulvalen durch oxidative Kupplung von Cyclopentadienid mittels Kupfer(II)-chlorid". Helvetica Chimica Acta. 69 (7): 1644–1654. doi:10.1002/hlca.19860690719.
- ^ Mark, V. (1966). "Perchlorofulvalene". Organic Syntheses. 46: 93. doi:10.15227/orgsyn.046.0093.