Bicyclo(6.2.0)decapentaene

Add links
Source: Wikipedia, the free encyclopedia.
Bicyclo[6.2.0]decapentaene
Names
IUPAC name
Bicyclo[6.2.0]deca-1(8),2,4,6,9-pentaene
Identifiers
3D model (
JSmol
)
ChemSpider
  • InChI=1S/C10H8/c1-2-4-6-10-8-7-9(10)5-3-1/h1-8H
    Key: FPEVLUDJYTXDPD-UHFFFAOYSA-N
  • C1=CC=CC2=C(C=C1)C=C2
Properties
C10H8
Molar mass 128.174 g·mol−1
Appearance red oil
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N (what is checkY☒N ?)

Bicyclo[6.2.0]decapentaene is a bicyclic organic compound and an isomer of naphthalene[1] and azulene.[2]

Whether this substance is an

antiaromatic, but when fused together the rings counteract each other.[3]

Formation

Bicyclo[6.2.0]decapentaene can be synthesised in a multistep process from bicyclo[4.2.0]octa-3,7-diene-2,5- dione. This is irradiated with ultraviolet producing a tricyclo decadiendione. This is then reduced to a diol with lithium aluminium hydride. The cis isomer then is converted to a tetraene by adding bromide or

hexadiene ring. When this is heated to 100 °C in benzene it converts to bicyclo[6.2.0]decapentaene, losing one bridge to form a cyclooctatetraene ring.[4] Another synthesis starts from octalene.[2]

Properties

Bicyclo[6.2.0]decapentaene has the appearance of orange-red crystals when solid at −78 °C.[2] In standard conditions it is a liquid red-orange oil.[4] Bicyclo[6.2.0]decapentaene dissolves in pentane.[2] Bicyclo[6.2.0]decapentaene reacts with oxygen in air. When heated to 100 °C it dimerizes by converting to a yellow oil that consists of three eight member unsaturated rings, an isomer of cyclooct[c]octalene.[4]

Bicyclo[6.2.0]decapentaene has, on average, a planar structure at room temperature. However, with minimal energy it can adopt a

tub shape where opposite sides of the ring are bent up in the same direction. The barrier to being non-planar is very low at 0.6 kcal/mol, so at standard conditions the ring is on average flat.[1] Unlike aromatic compounds, it has alternating bond lengths in the rings. One double bond is in the exclusive part of the four member ring (from carbon 9 to 10) and four double bonds are in the eight-member ring, at positions 1,3,5 and 7.[5] The bridging bond between carbon 1 and 8 is unusually long.[1] This bond has a π bond order of 0.1.[3] It may appear to follow Hückel's rule, but MMP2 calculations predict that it is anti-aromatic, with a resonance energy of -4.0 kcal/mol.[5] By contrast, HF/STO-3g and MNDOC calculations predict that it is slightly aromatic.[1] Bicyclo[6.2.0]decapentaene appears to have both rings acting independently, rather than as an aromatic whole 4n+2 π electron system.[6]

Derivatives

Bicyclo[6.2.0]decapentaene forms a complex with iron tricarbonyl. This has violet crystals and melts around 74-75 °C.[2]

Derivatives are known with side chains attached.[6] One example is 9,10-diphenyl bicyclo[6.2.0]decapentaene.[7]

References

  1. ^
    doi:10.1021/jo00215a018
    .
  2. ^
    doi:10.1002/anie.198310031
    .
  3. ^
    ISBN 9780470864012
    .
  4. ^
    doi:10.1016/S0040-4039(00)93636-0
    .
  5. ^
    S2CID 209647327.Open access icon
  6. ^
    S2CID 95730904
    .
  7. ISBN 9780306462429
    .

Extra reading
Retrieved from "https://en.wikipedia.org/w/index.php?title=Bicyclo(6.2.0)decapentaene&oldid=1170106137"