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### 2.7 - How to determine main structure if formal charges are equal?

Posted: Sat Nov 09, 2019 12:25 pm
Exercise 2.7 asks to draw all the resonance structures for the salt $N_{5}^{+}$ (a chain structure) and to indicate the most important structure (where there aren't any two like charges side-by-side). I drew the three structures, but all three structures have 2 N-atoms with FC = +1 and 1 N-atom with FC = -1. In this case, how do I determine the structure of lowest energy?

### Re: 2.7 - How to determine main structure if formal charges are equal?

Posted: Sat Nov 09, 2019 12:57 pm
Usually, it is best to have differing FC side by side (like a -1 next to +1) rather than the same FC side by side (like +1 next to +1) because it is unlikely that there would be two same charge centers in close proximity due to repulsive forces.

### Re: 2.7 - How to determine main structure if formal charges are equal?

Posted: Sat Nov 09, 2019 1:02 pm
The lowest energy structure would have the most electronegative N in the middle (-1 FC) and the two other N’s (+1 FC) on either side.