Answer:
There are two major resonance contributors for the en-amine. One contributor have no formal charges, only have one lone pair at N while the other one has positive and negative formal charges.
Explanation:
An en-amine is formed by the condensation reactions of aldehydes or ketone with secondary amine.
The contributor I have no formal charges. It has only one lone pair at Nitrogen atom.
The contributor II has +1 formal charges at N, and -1 formal charges at α Carbon.
Please see attachment. The resonance contributor are given.
