Bicalicene

Bicalicene is polycyclic hydrocarbon with chemical formula C16H8, composed of two cyclopentadiene and two cyclopropene rings linked into a larger eight-membered ring.[1] There are two isomers: cis-bicalicene and trans-bicalicene. It is a dimer of calicene.

trans-Bicalicene
Names
IUPAC names
(4aZ,8aZ)-Dicyclopenta[a,e]dicyclopropa[c,g][8]annulene
Dicyclopenta[a,e]dicyclopropa[c,g]cyclooctene
Identifiers
  • 73091-52-8
3D model (JSmol)
ChemSpider
  • InChI=1S/C16H8/c1-3-9-10(4-1)14-8-16(14)12-6-2-5-11(12)15-7-13(9)15/h1-8H/b13-9-,14-10-,15-11-,16-12-
    Key: FVDGMBFXSFSQOU-NONDJZLBSA-N
  • InChI=1/C16H8/c1-3-9-10(4-1)14-8-16(14)12-6-2-5-11(12)15-7-13(9)15/h1-8H/b13-9-,14-10-,15-11-,16-12-
    Key: FVDGMBFXSFSQOU-NONDJZLBBM
  • C1=CC2=C3C=C3C4=CC=CC4=C5C=C5C2=C1
Properties
C16H8
Molar mass 200.240 g·mol−1
Melting point 125–130 °C (dec)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
cis-Bicalicene
Names
IUPAC name
Dicyclopenta[a,c]dicyclopropa[e,g]cyclooctene
Identifiers
  • 122605-73-6
3D model (JSmol)
  • InChI=1S/C16H8/c1-3-9-10-4-2-6-12(10)14-8-16(14)15-7-13(15)11(9)5-1/h1-8H
    Key: MIGVZWUAYKWALJ-UHFFFAOYSA-N
  • C1=CC2=C3C=C3C4=CC4=C5C=CC=C5C2=C1
Properties
C16H8
Molar mass 200.240 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

Synthesis

Bicalicene is prepared by treatment of 1,2-bis(tert-butylthio)-3,3-dichlorocyclopropene with cyclopentadiene anion, followed by desulfurizing stannylation with tributyltin hydride and silica gel.[1]

Properties

trans-Bicalicene is polycyclic aromatic hydrocarbon, which is unusual for a 16 π electron ring system. Instead of a unified ring that Hückel's rule predicts would be anti-aromatic, the structure has a dominant partially-delocalized charge-separated structure consisting of four independently-aromatic rings: two as cyclopropenyl cations and two as cyclopentadienyl anions.[2]

cis-Bicalicene, by contrast, is an antiaromatic hydrocarbon.[3]

References
  1. Yonedo S, Shibata M, Kida S, Yoshida Z, Kai Y, Miki K, Kasai N (January 1984). "A Novel Aromatic Hydrocarbon with 16 π-Electron Periphery: "Cyclic Bicalicene"". Angewandte Chemie International Edition in English. 23 (1): 63–64. doi:10.1002/anie.198400631.
  2. Oziminski WP, Palusia M (2013). "Capturing the elusive aromaticity of bicalicene". Physical Chemistry Chemical Physics. 15 (9): 3286–3293. Bibcode:2013PCCP...15.3286O. doi:10.1039/C2CP43426A.
  3. Jelena Đurđević Nikolić; Ivan Gutman (2016). "A Comparative Study of the Two Isomers of Bicalicene". Polycyclic Aromatic Compounds. 38: 1–7. doi:10.1080/10406638.2016.1140659. S2CID 99213944.
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