Editing Ferrocene (section)

===Discovery===
Ferrocene was [[Role of chance in scientific discoveries|discovered by accident]] twice. The first known synthesis may have been made in the late 1940s by unknown researchers at [[Union Carbide]], who tried to pass hot cyclopentadiene vapor through an iron pipe. The vapor reacted with the pipe wall, creating a "yellow sludge" that clogged the pipe. Years later, a sample of the sludge that had been saved was obtained and analyzed by Eugene O. Brimm, shortly after reading Kealy and Pauson's article, and was found to consist of ferrocene.<ref name=werner2012/><ref name = Pauson2001 />

The second time was around 1950, when Samuel A. Miller, John A. Tebboth, and John F. Tremaine, researchers at [[BOC (company)|British Oxygen]], were attempting to synthesize amines from hydrocarbons and [[nitrogen]] in a modification of the [[Haber process]]. When they tried to react cyclopentadiene with nitrogen at 300&nbsp;°C, at atmospheric pressure, they were disappointed to see the hydrocarbon react with some source of iron, yielding ferrocene. While they too observed its remarkable stability, they put the observation aside and did not publish it until after Pauson reported his findings.<ref name=werner2012/><ref name=miller/><ref name=laszloRmon/> Kealy and Pauson were later provided with a sample by Miller ''et al.'', who confirmed that the products were the same compound.<ref name = Pauson2001 />

In 1951, [[Peter L. Pauson]] and [[Thomas J. Kealy]] at [[Duquesne University]] attempted to prepare [[fulvalene]] ({{chem2|(C5H4)2}}) by oxidative dimerization of [[cyclopentadiene]] ({{chem2|C5H6}}). To that end, they reacted the [[Grignard reagent|Grignard]] compound [[cyclopentadienyl magnesium bromide]] in [[diethyl ether]] with [[iron(III) chloride|ferric chloride]] as an oxidizer.<ref name=werner2012/> However, instead of the expected fulvalene, they obtained a light orange powder of "remarkable stability", with the formula {{chem2|C10H10Fe}}.<ref name = Pauson2001 /><ref name=pauson/>