Methylcyclopentadiene
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Methylcyclopentadiene describes three isomeric cyclic dialkenes with the formula C5MeH5 (Me = CH3). These isomers are the organic precursor to the methylcyclopentadienyl ligand (C5H4Me, often denoted as Cp′), commonly found in organometallic chemistry. C5MeH5 is prepared by thermal cracking its Diels–Alder dimer, followed by distillation to remove cyclopentadiene C5H6, a common impurity.