[synopsai]

Hi there,

I'm preparing for an organic chemistry exam and I'm wondering how I can draw resonance structures of following chemical compound.


I guess the nitrile group has a negative mesomeric effect, but if a transfer a bond to the N-atom that will result in a positive formal charge on the C-atom? And so you will get two C-atoms with a positive formal charge next to each other? Is that possible, or am I making a mistake with my resonance structures?

Thanks in advance for the help <3

[Hunter2]

No you can get( CH3)2C=C=N+. The positive charge travel from left C to the N.

[spirochete]

I would keep in mind that this is not a great ion to be drawing resonance structures for. Any other resonance structures that you draw will be making a very minor contribution to the structure. You could do what Hunter is suggesting, or you could also break the CN pi bond onto the N, creating two positive carbons.

Neither structure seems to suggest any stabilizing effect. In fact, the carbocation is quite destabilized by having the cyano group next to it, mainly because of the inductive effect I believe. Both resonance structures you end up drawing make a much smaller contribution to the structure than the originally draw one. Incomplete octet on nitrogen is terrible, two positive charges on carbon is terrible.

There doesn't seem to be much point to drawing these resonance structures without offering some kind of caveats like this.