EXPERIMENTAL MATRIX-ISOLATION AND THEORETICAL AB-INITIO HF 6-31G(D, P) STUDIES OF INFRARED-SPECTRA OF PURINE, ADENINE AND 2-CHLOROADENINE/

The results of ab initio calculations at the Hartree-Fock level with t he 6-31G(d, p) basis set are reported for the harmonic vibrational inf rared spectra of purine, adenine and 2-chloroadenine. These were compa red with the experimental IR spectra of the compounds isolated in low- temperature matrices. The experimental spectra of 2-chloroadenine are reported for the first time. In the case of purine this comparison res ulted in the complete assignment of the experimental IR spectrum. The proposed assignments of both the adenines studied are still incomplete .