Fulvalene
Fulvalene 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.
is a complex of the fulvalene dianion.History
An earlier attempt at synthesis of fulvalene in 1951 by Pauson and Kealy resulted in the accidental discovery of ferrocene. Its synthesis was first reported in 1958 by E. A. Matzner, working under William von Eggers Doering. In this method, cyclopentadienyl anion is coupled with iodine to the dihydrofulvalene which is then doubly deprotonated with n-butyllithium to the dianion and then oxidized with oxygen. Fulvalene was spectroscopically observed at 77 K from photolysis of diazocyclopentadiene with UV spectra matching those obtained by the Doering group. Final isolation of the compound came in 1986 via a method similar to that of Doering. The compound was found to be nonaromatic and extremely reactive above −50 °C through Diels-Alder dimerization.Derivatives
Perchlorofulvalene C10Cl8 is quite stable in contrast to the hydrocarbon. Tetrathiafulvalene is an organic semiconductor.
