What are ambident nucleophiles? Explain with detailed examples.

(N/A) Ambident nucleophiles are nucleophiles that possess two nucleophilic centers.
They can attack through either of the two sites.
Examples include cyanide $(CN^-)$ and nitrite $(NO_2^-)$ ions.
$1.$ Cyanide ion $(:C \equiv N:^-)$ can attack through the carbon atom to form alkyl cyanides $(R-CN)$ or through the nitrogen atom to form alkyl isocyanides $(R-NC)$.
- Reaction with $KCN$ (ionic) favors attack through $C$ to form $R-CN$.
- Reaction with $AgCN$ (covalent) favors attack through $N$ to form $R-NC$.
$2.$ Nitrite ion $(:O-N=O:^-)$ can attack through the oxygen atom to form alkyl nitrites $(R-ONO)$ or through the nitrogen atom to form nitroalkanes $(R-NO_2)$.
- Reaction with $NaNO_2$ (ionic) favors attack through $O$ to form $R-ONO$.
- Reaction with $AgNO_2$ (covalent) favors attack through $N$ to form $R-NO_2$.