Crystal structure of ammonium 3′-azido-3′-de­oxy­thymidine-5′-amino­carbonyl­phospho­nate hemi­hydrate: an anti-HIV agent

The asymmetric unit of the title compound, NH(4) (+)·C(11)H(14)N(6)O(7)P(−)·0.5H(2)O, contains one 3′-azido-3′-de­oxy­thymidine-5′amino­carbonyl­phospho­nate (ACP–AZT) anion, half of an NH(4) (+) cation lying on a twofold rotation axis and in another position, occupied with equal probabilities of 0.5, an NH(4) (+) cation and a water mol­ecule. The amide group of the ACP–AZT anion is disordered (occupancy ratio 0.5:0.5), with one part forming an N—H⋯O (involving C=O⋯H(4)N(+)) hydrogen bond and the other an O—H⋯N (involving C—NH(2)⋯OH(2)) hydrogen bond with the components of the split NH(4) (+)/H(2)O position. The pseudorotation parameters of ACP–AZT set it apart from previously studied AZT and thymidine. In the crystal, the various components are linked by N—H⋯O, O—H⋯O, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds, forming a three-dimensional framework.