Does Cyclopentadiene Have sp3 Hybridization While Its Cation and Anion Do Not?

[leopard]

Why is it that one of the C atoms of cyclopentadiene is sp³ hybridized? Because it's only involved in single bonds?

Why is it then that cyclopentadienyl cation and anion don't contain sp³ hybridized anions?

 

[Borek]

I would try to think in terms of resonance structures.