# Stability of keto-enol vs. conjugation

I am trying to figure out which tautomer of creatinine:

is more stable.

We see that the enol tautomer is more highly conjugated: the $\pi$ electrons from the alcohol to the double bond to the $\pi$ electrons of the Nitrogen to the imine to the final $\pi$ electrons of the amine.

In the keto form, we have the $\pi$ electrons from the carbonyl to the imine to the two amines.

I know the enol form is more conjugated, but in general I also know that the keto form is more stable. How do I reconcile this?

• I feel that you should also look at another possibility, that of having an aromatic pyrrole ring. I guess that's the most stable form. Nevertheless the real molecule will be a hybrid of all these. – Esha Manideep Nov 30 '18 at 15:57