Question

Which of the following is/are ambident nucleophiles?

• A. ${}^{-}C\equiv N$
• B. $N{O}_2^{-}$
• C. $PC{l}_5$
• D. $SnC{l}_4$

Answer 1

Answer: (A), (B)

The correct options are
A

${}^{-}C\equiv N$

B

$N{O}_2^{-}$

Nucleophilic reagent or nucleophile: Negatively charged species or a neutral molecule with lone pair of electron, i.e., with electron-rich centre. They act as Lewis base.

$Examples:$$\stackrel{\ominus }{O}H,\stackrel{\ominus }{O}R,\stackrel{\ominus }{C}N,\stackrel{\ominus }{N}{H}_2,\stackrel{\ominus }{H}\left(hydrideion\right),HS\stackrel{\ominus }{O_3},CO\stackrel{\ominus }{O}$

$R-C\equiv \stackrel{\ominus }{C},\stackrel{\ominus }{CH}(COOEt{)}_2,C{H}_3,\stackrel{\ominus }{COC{H}_2},H_2\stackrel{..}{O:},\underset{..}{\stackrel{..}{ROH}}$

$R-\underset{..}{\stackrel{..}{O}}-R,R-\underset{..}{\stackrel{..}{S}}-H,R-\stackrel{..}{N}{H}_2,\stackrel{..}{N}{H}_3$

$\stackrel{\ast }{R}MgX,\stackrel{\ast }{R}Li,LiAl\stackrel{\ast }{H_4}$

(Star indicates the atom that donates electron to the substrate.)

And what do you mean by ambident nucleophiles?
Ambident nucleophile: Species having two nucleophilic centres, of which ,one is neutral (complete octet and has at least one lone pair of electorns) and the other is charged (negative charge).

$\stackrel{\ominus }{C}\equiv \stackrel{..}{N},\stackrel{\ominus }{O}-\stackrel{..}{N}=O,\stackrel{\ominus }{O}-\underset{O}{\underset{\downarrow }{\stackrel{O}{\stackrel{\uparrow }{S}}}}-OH$