Crystal Structure of Alloxan Monohydrate: A Redetermination

Abstract

The structure of the title compound, C₄H₄N₂O₅, has been redetermined by single-crystal X-ray diffraction methods at c. 295 K. Crystals are triclinic, P1, a 8.217(2), b 6.809(2), c 5.765(4) Å, α 66.49(3),β 81.87(3), γ 74.35(2)º, Z= 2; the structure was refined by full-matrix least squares to a residual of 0.042 for 2190 independent 'observed' reflections, typical non-hydrogen interatomic distances being determined with estimated standard deviations of 0.001 Å. Together with the recent precise redetermination of the structure of alloxan , these results allow comparison of the geometries of essentially planar polycarbonyl (-hydrate) arrays with those of long-chain arrays previously recorded.