Animated Solution for Chemistry - Organic Chemistry: The correct pair(s) of the ambident nucleophiles is(are) A. AgCN/KCN B. RCOOAg/RCOOK C. AgNO${}_2$/KNO${}_2$ D. AgI/KI

To truly master organic chemistry, you must understand the behavior of nucleophiles. A nucleophile is an electron-rich species that seeks out an electron-deficient center (an electrophile) to form a chemical bond. But what happens when a single molecule has a "split personality"?

Imagine a molecule that has a choice. It possesses two entirely different atoms, both capable of donating an electron pair to form a bond. Such versatile and fascinating species are called ambident nucleophiles (from the Latin ambi meaning "both" and dent meaning "tooth"—they can bite from two different sides!).

Let's dive into the classic examples presented in this problem to see how they work in reality.

Carbon vs. Nitrogen

Look closely at the cyanide ion ($C{N}^{\ominus }$) derived from reagents like $KCN$ and $AgCN$. It is the poster child for ambident nucleophiles. The cyanide ion is a resonance hybrid of two structures:

Notice how the negative charge and lone pairs are distributed. The ion can attack an electrophile through its carbon atom or it can use the lone pair on its nitrogen atom.

Why does this matter? Because the reagent you choose dictates the product! - $KCN$ is predominantly ionic. It dissociates completely in solution to give free $C{N}^{\ominus }$ ions. Since a $C-C$ bond is stronger and more stable than a $C-N$ bond, the attack happens primarily through the carbon atom, yielding alkyl cyanides (nitriles). - $AgCN$, on the other hand, is predominantly covalent. The carbon atom is tightly bound to the silver atom, leaving only the nitrogen atom's lone pair available for attack. This results in the formation of alkyl isocyanides (isonitriles).

Oxygen vs. Nitrogen

Now, let's focus on the nitrite ion ($N{O}_2^{\ominus }$) from $KN{O}_2$ and $AgN{O}_2$. It shares a very similar story! The nitrite ion also exhibits resonance:

It can form a bond using the lone pair on the nitrogen atom, or it can attack through the negatively charged oxygen atom.

Just like with cyanide, the nature of the metal dictates the outcome: - $KN{O}_2$ is ionic, providing free nitrite ions. The attack occurs through the highly electronegative oxygen atom, producing alkyl nitrites ($R-O-N=O$). - $AgN{O}_2$ is covalent. The oxygen is bound to silver, forcing the attack to occur through the nitrogen atom's lone pair, which yields nitroalkanes ($R-N{O}_2$).

What about the carboxylate ion from $RCOOAg$ and the iodide ion from $KI$?

The carboxylate ion ($RCO{O}^{\ominus }$) does have two oxygen atoms. However, due to resonance, these two oxygen atoms are completely equivalent. It does not possess two different types of donor atoms that lead to structurally distinct linkage isomers. Therefore, it is not classified as an ambident nucleophile in this context.

The iodide ion ($I^{\ominus }$) is even simpler. It is a monatomic ion. With only one atom available to donate electrons, it is strictly a monodentate nucleophile.

By analyzing the options, we can confidently conclude that the pairs containing $KCN/AgCN$ and $KN{O}_2/AgN{O}_2$ are the ones featuring true ambident nucleophiles. This means statements A and C are correct, making option (c) our final, undeniable answer.