Pentamethylcyclopentadiene

Pentamethylcyclopenytadiene
Names
	Preferred IUPAC name 1,2,3,4,5-Pentamethylcyclopenta-1,3-diene
Identifiers
CAS Number	4045-44-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	70069 ;
ECHA InfoCard	100.021.586
PubChem CID	77667;
UNII	DSE3MRZ77C ;
CompTox Dashboard (EPA)	DTXSID00193466 ;
	InChI InChI=1S/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3 Key: WQIQNKQYEUMPBM-UHFFFAOYSA-N ; InChI=1/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3 Key: WQIQNKQYEUMPBM-UHFFFAOYAI;
	SMILES CC1=C(C)C(C)C(C)=C1C;
Properties
Chemical formula	C10H16
Molar mass	136.238 g·mol−1
Appearance	Colorless liquid
Odor	Mild
Density	0.87 g/cm3
Boiling point	55 to 60 °C (131 to 140 °F; 328 to 333 K) at 13 mmHg (1.7 kPa)
Solubility in water	Sparingly soluble
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Flammable
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H226
Flash point	114 °C (237 °F; 387 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

1,2,3,4,5-Pentamethylcyclopentadiene is a cyclic diene with the formula C₅(CH₃)₅H, often written C₅Me₅H, where Me is CH₃. It is a colorless liquid.

1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the ligand 1,2,3,4,5-pentamethylcyclopentadienyl, which is often denoted Cp* (C₅Me₅) and read as "C P star", the "star" signifying the five methyl groups radiating from the core of the ligand. Thus, the 1,2,3,4,5-pentamethylcyclopentadiene's formula is also written Cp*H. In contrast to less-substituted cyclopentadiene derivatives, Cp*H is not prone to dimerization.