Calicene

Calicene

File:Calicene.svg
Names
Preferred IUPAC name 5-(Cycloprop-2-en-1-ylidene)cyclopenta-1,3-diene
Other names Triapentafulvalene
Identifiers
CAS Number	6249-23-6
3D model (JSmol)	Interactive image
ChemSpider	26537418
ECHA InfoCard
E number
PubChem CID	12302244
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/C8H6/c1-2-4-7(3-1)8-5-6-8/h1-6H Key: ZXWMPJFQZJXFQN-UHFFFAOYSA-N
SMILES C1(C=CC=C1)=C2C=C2
Properties
Chemical formula	C8H6
Molar mass	102.136 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

Calicene or triapentafulvalene is a hydrocarbon of the fulvalene class with chemical formula C₈H₆, composed of a cyclopentadiene ring and a cyclopropene ring linked by a double bond. Its name is derived from the Latin calix meaning "goblet", from its shape.

Properties

Very high resonance energy is predicted by the Hückel method, however its resonance energy is not high. The central double bond is polarized with a partial positive charge on the carbon atom of triangular ring and a partial negative charge on the carbon atom of pentagonal ring, in keeping with added Hückel's rule stability of rings containing 2 π electrons and 6 π electrons respectively. Calicene's dipole moment has been computed to be 4.66 D. Several compounds that contains two or more calicene subunits are aromatic, such as trans-bicalicene (ring compound) or poly-2,7-[N]calicenes (chain compound)

Despite several attempts to prepare it, the parent calicene has so far defied attempts at synthesis. However, 1,2,3,4,5,6-hexaphenylcalicene has been prepared and an experimental dipole moment of 6.3 D was measured.