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Scott AP, Agranat I, Biedermann PU, et al. Fulvalenes, Fulvenes, and Related Molecules: An ab Initio Study. J Org Chem. 1997;62(7):2026-2038doi: 10.1021/jo962407l.
Scott, A. P., Agranat, I., Biedermann, P. U., Riggs, N. V., & Radom, L. (1997). Fulvalenes, Fulvenes, and Related Molecules: An ab Initio Study. The Journal of organic chemistry, 62(7), 2026-2038. https://doi.org/10.1021/jo962407l
Scott, Anthony P., et al. "Fulvalenes, Fulvenes, and Related Molecules: An ab Initio Study." The Journal of organic chemistry vol. 62,7 (1997): 2026-2038. doi: https://doi.org/10.1021/jo962407l
Scott AP, Agranat I, Biedermann PU, Riggs NV, Radom L. Fulvalenes, Fulvenes, and Related Molecules: An ab Initio Study. J Org Chem. 1997 Apr 04;62(7):2026-2038. doi: 10.1021/jo962407l. PMID: 11671506.
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J Org Chem. 1997 Apr 04;62(7):2026-2038. doi: 10.1021/jo962407l.

Fulvalenes, Fulvenes, and Related Molecules: An ab Initio Study.

The Journal of organic chemistry

Anthony P. Scott, Israel Agranat, P. Ulrich Biedermann, Noel V. Riggs, Leo Radom

Affiliations

  1. Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia, and Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.

PMID: 11671506 DOI: 10.1021/jo962407l

Abstract

Ab initio calculations using conventional (HF/6-31G and MP2/6-31G) and density functional theory (B-LYP/6-31G) methods have been used to determine the structures of the [n]fulvene and [n,m]fulvalene (n, m = 3, 5, 7) series of molecules, with particular emphasis on heptafulvalene (n = m = 7: 12). Calculations have also been performed on the parent cycloalkenes: cyclopropene, cyclopentadiene, and cycloheptatriene (1-3, respectively). All the fulvenes (n = 3, 5, 7: 4-6, respectively) and the smaller fulvalenes (n = 3, m= 3, 5, 7: 7-9, respectively, and n = m = 5: 10) are found to be planar. Pentaheptafulvalene (n = 5, m = 7: 11) adopts a very slightly nonplanar C(s)() arrangement of the five- and seven-membered rings. Heptafulvalene (12) is predicted to have an anti-folded C(2)(h)() structure, in accord with the X-ray crystal structure. We propose that the underlying reason for 11 and 12 adopting nonplanar conformations is the proximity of the H(2) and H(2)(') hydrogen atoms which promotes a distortion of the rings away from planarity at the central fulvalenic C=C double bond. In the process, pi-overlap is lost but this is partially regained by pyramidalization of the carbon centers in the seven-membered ring(s). The degree of folding is substantially more pronounced in 12 than in 11. Our calculated dipole moments, pi-electron distributions, bond alternation parameters, and energy comparisons indicate that the unknown smallest fulvalene, triafulvalene (7), is highly destabilized with localized bonding while triapentafulvalene (8), which is also unknown, is predicted to be stabilized and quite delocalized, consistent with Hückel 4n + 2 considerations.

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