Methylcyclopentadiene
Encyclopedia
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.
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.
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
(C5H4Me, often denoted as Cp'), commonly found in organometallic chemistry
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...
. C5MeH5 is prepared by thermal cracking its Diels-Alder dimer, followed by distillation to remove cyclopentadiene
Cyclopentadiene
Cyclopentadiene is an organic compound with the formula C5H6. This colorless liquid has a strong and unpleasant odor. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a Diels–Alder reaction...
C5H6, a common impurity.
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
Chirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
precursor complex (MeC5H4)Fe(CO)2)I exhibits only two MeC5H4 resonances in the 1H NMR spectrum
NMR spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained...
and three MeC5H4 resonances in the 13C NMR spectrum.