Question

In which of the following pairs, indicated bond has less bond dissociation energy?

• A. I
• B. II
• C. Both are equal
• D. Cannot determine

Answer 1

The correct option is A I

In compound (I) there is resonance between lone pairs on two nitrogen atoms and the double bond of the carbonyl group.
In compound (II) there is resonance between lone pair on one nitrogen atom and the double bond of the carbonyl group.
The resonance in compound (I) is more than in compound (II). The electrons are more delocalized in compound (I) than in compound (II).
Hence, the double bond character in compound (I) is smaller than in compound (II).