Butalene

Butalene
Names
Preferred IUPAC name
Bicyclo[2.2.0]hexa-1,3,5-triene
Other names
Butalene
Identifiers
3D model (JSmol)
UNII
  • InChI=1S/C6H4/c1-2-6-4-3-5(1)6/h1-4H
    Key: YHCJOCYHUDCVQI
  • c1cc2ccc12
  • C=1C=C2C=CC=12
Properties
C6H4
Molar mass 76.098 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Butalene is a polycyclic hydrocarbon composed of two fused cyclobutadiene rings.[1] A reported possible synthesis of it involves an elimination reaction from a Dewar benzene derivative. The structure itself can be envisioned as benzene with an internal bridge, and calculations indicate it is somewhat less stable than the open 1,4-didehydrobenzene biradical, the valence isomer in which that bridged bond is broken.

Structure and bonding

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Resonance is significant around the perimeter rather than through the middle.

Ab initio calculations indicate butalene has a planar geometry and, in keeping with a planar structure with 6 π-electron configuration, is aromatic. Thus, the most significant π bonding interactions involve conjugation around the periphery of the whole six-atom structure, similar to benzene, rather than cross-ring resonance along the bridging bond.[2] Significant resonance around one or the other four-membered ring alone would be a less-stable antiaromatic form, as is seen in cyclobutadiene itself.

See also

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References

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  1. ^ Warner, Philip M.; Jones, Graham B. (2001). "Butalene and Related Compounds: Aromatic or Antiaromatic?". J. Am. Chem. Soc. 123 (42): 10322–10328. doi:10.1021/ja011134v. PMID 11603982.
  2. ^ Sakai, Shogo; Udagawa, Taro; Kita, Yuki (2009). "Theoretical Studies on the Structures and the Aromaticity for Condensed Cyclobutadienoids Series: The Combination of Kekulé Structures". J. Phys. Chem. A. 113 (50): 13964–13971. doi:10.1021/jp906258e. PMID 20000386.