These isomers are the organic precursor to the methylcyclopentadienyl ligand (C5H4Me, often denoted as Cp′), commonly found in organometallic chemistry.

[1] Deprotonation of methylcyclopentadiene gives the aromatic methylcyclopentadienyl anion.

There is therefore no symmetry within the ring even accounting for rotation around the ring–metal axis, but instead there is a diastereotopic relationship as a result of being part of a chiral complex.

The achiral precursor complex Cp′Fe(CO)2I has only two signals for those hydrogens and three for those carbons, indicating a symmetric structure.

[3] MgCpBr (TiCp2Cl)2 TiCpCl3 TiCp2S5 TiCp2(CO)2 TiCp2Me2 VCpCh VCp2Cl2 VCp(CO)4 (CrCp(CO)3)2 Fe(η5-C5H4Li)2 ((C5H5)Fe(C5H4))2 (C5H4-C5H4)2Fe2 FeCp2PF6 FeCp(CO)2I CoCp(CO)2 NiCpNO ZrCp2ClH MoCp2Cl2 (MoCp(CO)3)2 RuCp(PPh3)2Cl RuCp(MeCN)3PF6