Methylcyclopentadiene

Methylcyclopentadiene
Identifiers
ChemSpider 60141 Yes
Jmol-3D images Image
PubChem 66775
Properties
Molecular formula
 C6H8
Molar mass 80.13 g·mol−1
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Methylcyclopentadiene describes three isomeric cyclic diolefins 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.[1]

Relative to the corresponding Cp complexes, complexes of Cp' exhibit enhanced solubility in organic solvents. Furthermore Cp' is often employed to probe the structure of organometallic complexes. For example, (MeC5H4)Fe(PPh3)(CO)I, exhibits four MeC5H4 resonances in its 1H NMR spectrum and five MeC5H4 resonances in the 13C NMR spectrum. Free rotation of the Cp' ligand does not equivalence the diastereopic protons and carbon centers. The achiral precursor complex (MeC5H4)Fe(CO)2)I exhibits only two MeC5H4 resonances in the 1H NMR spectrum and three MeC5H4 resonances in the 13C NMR spectrum.[2]

Structure of (MeC5H4)Fe(PPh3)(CO)I, with labels for the four diastereotopic ring protons.

References

  1. ↑ Darkwa, James; Giolando, Dean M.; Murphy, Catherine Jones; Rauchfuss, Thomas B.; Müller, A. (1990). "Bis(η5-Methylcyclopentadienyl)Titanium Pentasulfide, Bis(μ-Methylcyclopentadienyl)-Divanadium Pentasulfide, and Bis(μ5-Methylcyclopentadienyl)Divanadium Tetrasulfide". Inorg. Synth. 27: 51. doi:10.1002/9780470132586.ch10.
  2. ↑ Carlton, L.; Johnston, P.; Coville, N. J. (1988). "Substituted cyclopentadienyl complexes. II. Carbon-13 NMR spectra of some [(η5-C5H4Me)Fe(CO)(L)I] complexes". Journal of Organometallic Chemistry 339 (3): 339–43. doi:10.1016/S0022-328X(00)99395-1.

See also