Abstract: NMR chemical shifts of C8 adduct in the reaction of guanosine with N-acetyl-4-biphenyl nitrenium ion were studied using ab initio calculations. The results were in good agreement with experimental data. Additionally, the charges obtained by atom-bond electronegativity equalization method σπ (ABEEM σπ) also corresponded with the NMR chemical shifts. For imine adduct in the reaction of adenosine with N-acetyl-4-biphenyl nitrenium ion, theoretical NMR chemical shifts of some key C atoms were very different to the experimental values. Hence, it was predicted that the final adduct in studied reaction should include azepine adduct besides imine adduct.

Key words: Imine adduct, Charge, NMR chemical shift