Frost circles cyclopentadienyl anion

Show how you could adapt Frost s circle to generate the orbital lagram shown in Figure 11.15 for cyclopentadienyl anion. 

Cyclopentadiene is a muci stronger acid than propene. The difference in acidity is enormous. Look carefully at the structure of the cyclopentadienyl anion. Here too, we have a planar, cyclic, and fully conjugated system. The molecular orbitals can be derived from a Frost circle (Fig. 13.29).There are six electrons to put into the molecular orbitals, and, as in the tropylium ion or benzene, they fully occupy the lowest molecular orbital and the set of degenerate bonding molecular orbitals. The cyclopentadienyl anion can be described as aromatic, and for an anion, this species is remarkably stable. Do not fall into the trap of expecting this anion to be as stable as benzene. 

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See also in sourсe #XX -- [ ]

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