2'-Deoxycytidine-N(3)-cyanoborane Monohydrate

The structure of the title compound, [4-amino-1-(2-deoxy-β-D-ribofuranosyl)-2-oxo-(1H)-3-pyrimidinio](cyano)borate, C₁₀H₁₅BN₄O₄.H₂O, features an interaction of 2.05 (4) Å between an H atom of the —BH₂CN group and an H atom of the —NH₂ group. The —C≡N group does not lie in the cytosine plane, the N atom being 2.24 Å away from the plane. The cytosine rings are stacked with almost complete overlap along the twofold screw axis with an interplanar separation of 4.03 Å. The sugar is in the ₄³T puckering mode, the C(5′)—O(5′) bond has the gg conformation and the relative orientation of the sugar and the base is anti.