Question
Question: The -CN group exhibits which of the following electronic effects: +m effect, -m and +i, or -i?...
The -CN group exhibits which of the following electronic effects: +m effect, -m and +i, or -i?
A
+m effect
B
-m and +i
C
-i
Answer
-i
Explanation
Solution
The -CN group exhibits both a -M effect (electron withdrawal through pi bonds) and a -I effect (electron withdrawal through sigma bonds due to the electronegativity of nitrogen). It does not exhibit a +M effect because the lone pair on nitrogen is involved in the triple bond and is not readily available for donation. It does not exhibit a +I effect; it exhibits a -I effect. Therefore, among the given options, only the -i effect is a correct description of an electronic effect exerted by the -CN group.