CD(ALLOXANTHINE)2(NO3)2(H2O)2

The title complex, diaquadinitratobis{[1H]pyrazolo-[3,4-d]pyrimidine-4,6(5H,7H)-dione-N1}cadmium-(II), was prepared as part of a study of the coordinating properties of the xanthine oxidase inhibiting molecule, alloxanthine. [Cd(NO3)2(C5H4-N4O2)2(H2O)2] contains monomeric centrosymmetric units with the Cd ion octahedrally coordinated by two NO3 groups, two H2O molecules and by two alloxanthine ligands. Alloxanthine coordinates monodentately through the pyrazole N atom N(9). The H atoms of the 'neutral alloxanthine molecule are bonded to the other atoms N(1), N(3) and N(8). The molecular structure is stabilized by intramolecular bifurcated hydrogen-bonding contacts of the type N-H...O, forming indirect chelates.