I have studied that as electronegativity increases nucleophilicity decreases. But in the aprotic solvent the order of nucleophilicty is: $$\ce{F- > Cl- > Br- > I-}$$ but how is this possible as $\ce{F-}$ is strongly electronegative as well as a strong nucleophile Isn't this contradictory? There is no effect of the aprotic solvent on anions.

Information given : This causes the most confusion, because it is solvent-dependent. In polar protic solvents (e.g. water and alcohols, any solvent with OH) nucleophilicity increases as you go down the periodic table (F- < Cl- < Br- < I – ). In polar aprotic solvents (e.g. DMSO, acetone) the order is reversed, and the most basic nucleophiles are also the most nucleophilic. (F- > Cl – > Br – > I – ).

On https://www.masterorganicchemistry.com/tips/what-makes-a-good-nucleophile/

I want to know why my concept is wrong.

  • $\begingroup$ Just to make sure I understand: did you just claim that iodide is not the best nucleophile in that series? $\endgroup$ – Zhe May 11 '18 at 13:04
  • $\begingroup$ @Zhe yes I am claiming that in aprotic solvent . $\endgroup$ – INter May 11 '18 at 14:41
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    $\begingroup$ Where did you see the information suggesting this trend? This is counter to my understanding, and I'm guessing it is counter to many others' understanding here based on Zhe's response. $\endgroup$ – SendersReagent May 11 '18 at 15:13
  • $\begingroup$ @SendersReagent masterorganicchemistry.com/tips/what-makes-a-good-nucleophile $\endgroup$ – INter May 11 '18 at 16:17
  • $\begingroup$ @Zhe chemistry.umeche.maine.edu/CHY251/Ch7-Overhead4.html $\endgroup$ – INter May 11 '18 at 16:17