Although carbocations are alwaysplanar but carbanions and free radicals can assume either planar or pyramidal geometry. Why is it so ? Explain.

Although carbocations are alwaysplanar but carbanions and free radical

1.	Although carbocations are alwaysplanar but carbanions and free radicals can assume either planar or pyramidal geometry. Why is it so ? Explain.
Answer» Solution :The simple alkyl carbanions are pyramidal. For example, However, carbanions in which the C-atom carrying the NEGATIVE charge is adjacent to a double bond or a benzene ring, are planar due to stabilization by RESONANCE. Thus, allyl and benzyl carbanions are planar. Most of the free radicals are planar but free radicals in which the carbon atom carrying the ODD ELECTRON is connected to a bridge head carbon or highly electronegative element are pyramidal. For examples. `CF_(3)` has pyramidal shape.