Ambident Nucleophiles

[Carrie Huang 2F]

How do I determine whether or not a nucleophile is ambident?

[Chem_Mod]

Can you explain your question further or give an example?

[Jeannie Huang 3B]

By definition, an ambident nucleophile is a molecule that has available lone pairs of electrons on two or more of its atoms--in other words, 2 places on it where it can react with another molecule.
Draw out the Lewis structures to see. (It's similar to the idea of a bidentate ligand from 14A).

Refer to page 145 of the Introduction to Organic Chemistry book.

Taking examples from pg 145 and 189 (the hw),

Look at the Lewis structure of SCN-. It has lone pairs on S and N, thus it is an ambident nucleophile (can be a nitrogen nucleophile or a sulfur nucleophile, either atom could react with an electrophile).
Same with CN-. It's an ambident nucleophile because it has lone pairs on both the C and N.
H20 and CH30- are not ambident nucleophiles because they both only have lone pairs on oxygen. NH2CH3 isn't either because only has a lone pair on its nitrogen and no other atom.
F- obviously isn't an ambident nucleophile because it's only one atom.