Ricerc@Sapienza

Seven 5-and 6-halogenated derivatives of uracil or 1-methyluracil (halogen = Cl, Br, I) were
studied by single crystal X-ray diffraction. In contrast with pure 5-halouracils, where the presence
of N-H…O and C-H…O hydrogen bonds prevents the formation of other intermolecular interactions,
the general ability of pyrimidine nucleobases to provide electron donating groups to halogen
bonding was confirmed in three crystals and cocrystals containing uracil with the halogen atom at