A density functional theory study of vibrational infrared spectra of N-methyl-P tautomers

The results of the first theoretical calculations of the vibrational infrared spectra of three tautomers of N-methylated P base, which is an analog of nucleic acid bases, have been reported. All geometry optimizations and infrared spectra calculations have been performed at B3LYP level of theory using cc-pVDZ basis set. The differences in the spectra of tautomers are attributed primarily to the proton being bonded to either oxygen (enol form) or nitrogen (amino and imino forms) atoms. Some of the vibrations have been predicted to be different in amino form due to a much more bent structure of the ring as compared to that in the imino and enol forms.