In the title compound, 6-amino-5-hydroxyimino-1-methyl-2,4(1H, 3H)-pyr
imidinedione hydrate, C6H8N4O3.-H2O, the uracil moieties are linked by
N-H ... O hydrogen bonds [N ... O 2.814(3) Angstrom] resulting in cen
trosymmetric base-paired dimers which are then linked in a three-dimen
sional network bonding with a water molecule [N ... O 3.105(3), O ...
O 2.748(3) and 2.817(3), and 2.873 (3) Angstrom]. There is also an int
ramolecular N-H ... N hydrogen bond [N .... N 2.680(3) Angstrom] betwe
en adjacent amino and hydroxyimino groups. All available hydrogen-bond
donors are utilized.