Structures of 2 nucleoside analogs - 1-[(2R,6R)-6-hydroxymethyl-1,4-dioxan-2-yl]uracil and 5-bromo-1-[(2R,6R)-6-hydroxymethyl-1,4-dioxan-2-yl]uracil

(I) 1-[(2R,6R)-6-Hydroxymethyl-1,4-dioxan-2-yl]uracil, C9H12N2O5, M(r) = 228.20, trigonal, P3(1)21, a = 9.438 (5), c = 19.77 (2) angstrom, V = 1522 (2) angstrom 3, Z = 6, D(m) = 1.49, D(x) = 1.494 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 0.115 mm-1, F(000) = 720, T = 293 K, final R = 0.036 for 1541 unique observed [F greater-than-or-equal-to 4-sigma(F)] reflections. (II) 5-Bromo-1-[(2R,6R)-6-hydromethyl-1,4-dioxan-2-yl]uracil, C9-H11BrN2O5, M(r) = 307.10, triclinic, P1, a = 4.851 (4), b = 6.409 (5), c = 9.687 (9) angstrom, alpha = 70.78 (7), beta = 83.54 (7), gamma = 80.01 (6)-degrees, V = 279.5 (4) angstrom 3, Z = 1, D(m) = 1.82, D(x) = 1.824 Mg m-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 3.649 mm-1, F(000) = 154, T = 293 K, final R = 0.036 for 959 unique observed reflections [F greater-than-or-equal-to 4-sigma(F)]. Except for N-glycosidic torsion angle, which is 230.9 (2)-degrees for (I) and 210.2 (7)-degrees for (II), the two molecules are conformationally very similar. No intramolecular hydrogen bonds are observed. The crystal packings are stabilized by intermolecular hydrogen bonds and base-stacking forces.status: publishe