Cyclopentadienyl anion

Cyclopentadienyl anion
Identifiers
CAS Number	12127-83-2;
3D model (JSmol)	Interactive image;
ChemSpider	2731064;
PubChem CID	3490527;
CompTox Dashboard (EPA)	DTXSID601027108 ;
	InChI InChI=1S/C5H5/c1-2-4-5-3-1/h1-5H/q-1 Key: SINKOGOPEQSHQD-UHFFFAOYSA-N; InChI=1/C5H5/c1-2-4-5-3-1/h1-5H/q-1 Key: SINKOGOPEQSHQD-UHFFFAOYAD;
	SMILES [cH-]1cccc1;
Properties
Chemical formula	[C5H5]− or Cp−
Molar mass	65.09 g/mol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

In chemistry, the cyclopentadienyl anion or cyclopentadienide is an aromatic species with a formula of [C₅H₅]⁻ and abbreviated as Cp⁻.^[1] Its name derives from the molecule cyclopentadiene. Salts of the cyclopentadienyl anion can be stable, e.g., Sodium cyclopentadienide. more complex coordination compounds are known as cyclopentadienyl complexes, such as metallocene

It is a regular pentagonal, planar, cyclic ion; as well, it has 6 π-electrons (4n+2, where n=1), which fulfills Hückel's rule of aromaticity. It can coordinate as a ligand to metal atoms.

The structure shown is a composite of five resonance contributors in which each carbon carries part of the negative charge.

References

^ "Cyclopentadienide". PubChem Compound Database. National Center for Biotechnology Information. Retrieved 14 April 2016.

[Cyclopentadienide-1] "Cyclopentadienide". PubChem Compound Database. National Center for Biotechnology Information. Retrieved 14 April 2016.

[1]

See also

References