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

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

References

  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.
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