A theoretical study at the B3LYP/6-31++G(d,p) level was performed on the tatumerization of 7H-purine-2, 6-diamine into 9H-purine-2, 6-diamine. Such a tautomerism can take place via three different pathways namely A, B, and C. The energetic results associated with the gas phase reveal that pathways A, B, and C display a very high activation Gibbs free energy of 45.1, 68.6 and 48.9 kcal/mol, resp...
