1,N6-etheno-2'-deoxytubercidin hemihydrate

The title compound [systematic name: 7-(2-deoxy-β-D-erythro-pentofuranosyl)-7H-imidazo[1,2-c]pyrrolo[2,3-d]pyrimidine hemihydrate], 2C(13)H(14)N(4)O(3)·H(2)O or (I)·0.5H(2)O, shows two similar conformations in the asymmetric unit. These two conformers are connected through one water molecule by hydrogen bonds. The N-glycosylic bonds of both conformers show an almost identical anti conformation with χ = -107.7 (2)° for conformer (I-1) and -107.0 (2)° for conformer (I-2). The sugar moiety adopts an unusual N-type (C3'-endo) sugar pucker for 2'-deoxyribonucleosides, with P = 36.8 (2)° and τ(m) = 40.6 (1)° for conformer (I-1), and P = 34.5 (2)° and τ(m) = 41.4 (1)° for conformer (I-2). Both conformers and the solvent molecule participate in the formation of a three-dimensional pattern with a `chain'-like arrangement of the conformers. The structure is stabilized by intermolecular O-H...O and O-H...N hydrogen bonds, together with weak C-H...O contacts.