# Why doesn't fluoride ion have highest nucleophilic power (nucleophilicity)?

As you can see from the image above,

• '$\ce{R3C}$' anion has 1 lone pair
• '$\ce{R2N}$' anion has 2 lone pairs
• $\ce{RO}$ anion has 3 lone pairs
• $\ce{F}$ anion has 4 lone pairs

According to VSEPR theory,

lone pair-lone pair repulsion > bond pair-lone pair repulsion > bond pair-bond pair repulsion

As fluoride ion has the greatest number of lone pairs (= 4), it should suffer from highest number of lone pair-lone pair repulsions.

In order to reduce its lone pair-lone pair repulsions and thus its unstability, shouldn't it donate its lone pair more readily than other anions? Thereby, shouldn't fluoride ion have more nucleophilic tendency than the other (mentioned) anions?

Among the nucleophiles you have stated, $\ce{R3C}$ anion would be the best nucleophile in a polar protic solvent. However, if you use a polar aprotic solvent, flouride ion would behave as a very good nucleophile (because aprotic solvents do not solvate anions).