Question

Which of the following groups have –I effect?
This question has multiple correct options.
A. $$-N^{+}{(C{H}_3)}_3$$
B. $-N^{+}{H}_3$
C. $-O^{-}$
D. $-CO{O}^{-}$

Answer 1

Hint: In order to have a negative inductive effect, a species should be electron deficient, which also makes it an electrophile. The electron deficiency may give the species a positive charge, hence it easier to identify the effect it will show.
Inductive effect can determine the acidic or basic nature of a molecule, as the electron donors will be basic and acceptors will be acidic as per the Lewis acid base theory.

Complete answer:
> The inductive effect can be defined as an experimentally observable effect of the charge transfer through a chain of atoms under observation by the phenomena of electrostatic induction.
> In other words it is the polarization of a bond because the effect of electron withdrawal or electron donation of atoms or adjacent groups is termed as an inductive effect.
> Negative inductive effect or the –I effect as per the question, is the electron withdrawing nature of the functional groups or atoms which are present. It is denoted by the symbol -I. We can consider some of the examples of groups in the decreasing order of their -I effect.
> Electron withdrawing groups are having negative inductive effect (-I)

$$N{H}^{3+}>N{O}_2>CN>S{O}_{3}H>CHO>CO>COOH>COCl>CON{H}_2>F>Cl>Br>I>OH>OR>N{H}_2>C_6{H}_5$$

> We can see that least amount of –I effect is shown by $$N{H}_2$$ group as it has lesser electron withdrawing tendency because of presence of lone pair of electrons. And $$N{H}^{3+}$$ has the most electron withdrawing tendency hence it shows most –I effect.
> In the given question if we consider the first option, we can see the positive charge which is present in the nitrogen of the species. This indicates that the whole ion is electron deficient in nature, hence it will attract electrons so it will show a negative inductive effect.
> Similarly, if we look at the second option, we see the same kind of ion, where nitrogen is carrying a positive charge, so it will attract electrons, hence showing a negative inductive effect. But if we look at the later species given in the option, we see that it contains negative charge, which means it has a high abundance of electrons, so it will have a tendency to donate electrons rather than accepting them. So they would not show a negative inductive effect.

So, the correct answer is Option A,B.

Note: 

> With the use of inductive effect, we can predict the acidic or basic nature of compounds. Generally we can say that the electron withdrawing groups are responsible for increasing the acidity in a compound and presence of the electron donating group decreases it.
> Inductive effect should not be confused with electrometric effect which can be observed only in pi bonds and are a sort of temporary effect, and requires electrophilic attack for its existence.