7-Fluorotubercidin: a halogenated derivative of a naturally occurring nucleoside antimetabolite

The title compound [systematic name: 4-amino-5-fluoro-7-(beta-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine], C(11)H(13)FN(4)O(4), exhibits an anti glycosylic bond conformation, with a chi torsion angle of -124.7 (3) degrees. The furanose moiety shows a twisted C2'-endo sugar pucker (S-type), with P = 169.8 (3) degrees and tau(m) = 38.7 (2) degrees. The orientation of the exocyclic C4'-C5' bond is +sc (gauche, gauche), with a gamma torsion angle of 59.3 (3) degrees. The nucleobases are stacked head-to-head. The extended crystal structure is a three-dimensional hydrogen-bond network involving O-H...O, O-H...N and N-H...O hydrogen bonds. The crystal structure of the title nucleoside demonstrates that the C-C bonds nearest the F atom of the pyrrole system are significantly shortened by the electronegative halogen atom.