Theoretical study of the ground state intramolecular proton transfer in cytidines

Abstract EN

Four isomers of 1-methyl-N-methoxycytosine and their mutual interconversion were studied theoretically at the B3LYP level using variety of basis sets and a different number of polarization and diffuse functions.

It was found that the imino form of the studied molecule is the most stable form within the tautomeric mixture.

Transition state of interconversion were studied at the B3LYP/6-31G(d,p) level of theory .

The study has shown the exclusion the possibility of direct proton transfer in the gas phase due to the strain in the fourcentered transition state, in which the proton being transferred is forced to come close to the positively charged carbon atom at the opposite corner of the four-membered ring.