4 research outputs found
1,3,7-Trimethyl-2,4-dioxo-1,2,3,4-tetraÂhydroÂpteridine-6-carboxylic acid hemihydrate
In the title compound, C10H10N4O4·0.5H2O, the two rings of the pteridine system are nearly coplanar [dihedral angle = 4.25 (9)°]. The atoms of the carboxyl group are also coplanar with the pteridine unit [r.m.s. deviation from the mean plane of the pteridine skeleton = 0.092 (2) Å]. In the crystal, the presence of the water molecule of crystallization (O atom site symmetry 2) leads to a hydrogen-bonding pattern different from the one shown by many carboxylic acid compounds (dimers formed through O—Hâ‹ŻO hydrogen bonds between neighbouring carboxyl groups): in the present structure, the water molÂecule, which lies on a binary axis, acts as a bridge between two molÂecules, forming a hydrogen-bonded dimer. In addition to the hydrogen bonds, there are π–π ring stacking interÂactions involving the pyrimidine and pyrazine rings [centroid–centroid distance = 3.689 (1)Ă…], and two different pyrazine rings [centroid–centroid distance = 3.470 (1)Ă…]. Finally, there is a C—Oâ‹ŻĎ€ contact involving a carboxylÂate C—O and the pyrimidine ring with a short Oâ‹ŻCg distance of 2.738 (2) Å
ContribuciĂłn al estudio clĂnico de la miocardiopatĂa diabĂ©tica /director Mariano ValdĂ©s Chavarri, Francisco Javier Tebar MassĂł.
Tesis-Universidad de Murcia.MEDICINA ESPINARDO. DEPOSITO. MU-Tesis 219.Consulte la tesis en: BCA. GENERAL. ARCHIVO UNIVERSITARIO. T.M.-532