Three trans-Diphenylperfluorotrienes

The structures of (E)-1,1,1,6,6,6-hexafluoro-2,5-bis(pentafluorophenyl)- 2,3,4-hexatriene, (1), C₁₈F₁₆, (E)-1,1,1,2,2,7,7,8,8,8-decafluoro-3,6-diphenyl-3,4,5-octatriene, (2), C₂₀H₁₀F₁₀, and (E)-1,1,1,2,2,3,3,8,8,9,9,10,10,10-tetradecafluoro-4,7-diphenyl- 4,5,6-decatriene, (3), C₂₂H₁₀F₁₄, confirm the trans conformation assigned by spectrophotometric methods. These trienes exhibit the central double shortening observed in cumulenes. The phenyl rings are rotated slightly from the triene plane in (2) and (3) and are nearly perpendicular to the triene plane in (1). The large rotation of the perfluorophenyl rings from the triene plane is due to intramolecular steric interactions with the ortho-F atoms.

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