Structure of 5-azauracil (C₃H₃N₃O₂) and its hydrolysis product

The title compounds cocrystallize in space group P-1:a=8.773(3), b=9.14(3), c=14.062(4) Å, α=81.38(7), β=71.76(3), γ=82.96(8)°, U=1055.5 ų, Z=4 (two independent molecules each of azauracil, its hydrolysis product, and water in the asymmetric unit). The structure was solved by direct methods and refined by full-matrix least-squares methods to R=0.059 for 2911 observed reflections. Unusually, the crystal contains both the parent molecule and its hydrolysis product in a hydrogen-bonded complex. The hydrogen bonding results in the formation of essentially planar layers of molecules which are held together by dispersion forces.