Cyclopentadienone

Cyclopentadienone is an organic compound with molecular formula C₅H₄O. The parent cyclopentadienone is rarely encountered, because it rapidly dimerizes.^[1] Many substituted derivatives are known, notably tetraphenylcyclopentadienone. Such compounds are used as ligands in organometallic chemistry.^[2]

The Knölker complex, derived from a substituted cyclopentadienone, is a catalyst for transfer hydrogenation.^[3]

Cyclopentadienone

Names
Preferred IUPAC name Cyclopenta-2,4-dien-1-one
Identifiers
CAS Number	13177-38-3
3D model (JSmol)	Interactive image
ChemSpider	122931
PubChem CID	139405
CompTox Dashboard (EPA)	DTXSID80157203
InChI InChI=1S/C5H4O/c6-5-3-1-2-4-5/h1-4H Key: FQQOMPOPYZIROF-UHFFFAOYSA-N InChI=1/C5H4O/c6-5-3-1-2-4-5/h1-4H Key: FQQOMPOPYZIROF-UHFFFAOYAD
SMILES C1=CC(=O)C=C1
Properties
Chemical formula	C5H4O
Molar mass	80.086 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Cyclopentadienone can be generated by the photolysis or pyrolysis of various substances (e.g. 1,2-benzoquinone^[4]), and then isolated in an argon matrix at 10 K (−263 °C). It dimerizes readily upon thawing the matrix at 38 K (−235 °C).^[5][6]

See also

• Dienone