What are some examples of nucleophiles and strong bases?
With a few exceptions, a strong nucleophile is also a strong base.
All nucleophiles are Brønsted bases — they donate a pair of electrons to form a bond to another atom.
If they bond to a hydrogen atom, we call them bases. If they bond to any other atom (especially carbon), we call them nucleophiles.
Strong Bases/Strong Nucleophiles
A good base is usually a good nucleophile. So, strong bases — substances with negatively charged O, N, and C atoms — are strong nucleophiles.
Examples are: RO⁻, OH⁻, RLi, RC≡C:⁻, and NH₂⁻.
Strong Bases/Poor Nucleophiles
Some strong bases are poor nucleophiles because of steric hindrance.
Examples are t-BuO⁻, t-BuLi, and LiN[CH(CH₃)₂]
Weak Bases/Good Nucleophiles
I⁻ is a weak base, but it is a good nucleophile because the large electron cloud is highly polarizable.