Chaotic Systems: π- vs σ- Distortivity

"We noted the fine balance between the tendency to distort (by the π-electrons) and the resistance toward distorsion of the σ-frame; a very tiny change in the π-distortivity changes the n (in CnHn) in which the distortion nests in."

  1. ΔE(σ + π) = 5.0(2n+1) - 5.4(2n); Bond alternation (ΔE < 0) starts at n=7 (C30H30)
  2. ΔE(σ + π) = 5.0(2n+1) - 6.0(2n); Bond alternation starts at n=3 (C14H14)

S. S. Shaik and P. C. Hiberty, "A Chemist's Guide to Valence Bond Theory", Wiley, 2007. ISBN 978-0-470-03735-5; Shaik, S.; Shurki, A.; Danovich, D.; Hiberty, P. C., "A different story of benzene," J. Mol. Struct: THEOCHEM, 1997, 398-399, 155-167, DOI: 10.1016/S0166-1280(96)04934-2.