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Fluorenyldiene 1 is a highly conjugated, planar molecule
Chapter 18, Problem 18.75(choose chapter or problem)
Fluorenyldiene 1 is a highly conjugated, planar molecule that is readily oxidized to dication 2 (J. Org. Chem. 2002, 67, 7029 7036). 1 2 ! ! 2e (a) Draw at least four other resonance structures of dication 2 and identify why the resonance structure shown here is the greatest contributor to the overall resonance hybrid, despite the presence of neighboring like charges (which is generally a destabilizing factor). (b) Explain why the lowest energy conformation for 2 is not planar and instead exhibits a perpendicular arrangement between the two ring systems.
Questions & Answers
QUESTION:
Fluorenyldiene 1 is a highly conjugated, planar molecule that is readily oxidized to dication 2 (J. Org. Chem. 2002, 67, 7029 7036). 1 2 ! ! 2e (a) Draw at least four other resonance structures of dication 2 and identify why the resonance structure shown here is the greatest contributor to the overall resonance hybrid, despite the presence of neighboring like charges (which is generally a destabilizing factor). (b) Explain why the lowest energy conformation for 2 is not planar and instead exhibits a perpendicular arrangement between the two ring systems.
ANSWER:Step 1 of 3
Hyperconjugation is the permanent result of the localization of the sigma electrons of the carbon-hydrogen bond of an alkyl group in the presence of an unsaturated system or an unshared 
A carbocation will be stabilized by hyperconjugation. The positive charge will then be distributed out as a result of this. Greater hyperconjugation will occur in structures with more alkyl groups.