Trimethyl-ammonium 5-(2,4-dinitro-phenyl)-2,6-dioxo-1,2,3,6-tetra-hydro-pyrimidin-4-olate 0.125-hydrate.

The asymmetric unit of the title salt C3H10N(+)·C10H5N4O7 (-)·0.125H2O [trivial name: trimethyl-ammonium 5-(2,4-dinitro-phen-yl)barbiturate 0.125-hydrate], contains two independent cations, two independent anions and a 0.25-occupancy solvent water mol-ecule. In one of the cations, the C atoms are disordered over two sets of sites with refined occupancies of 0.538 (8) and 0.462 (8). In the anions, the dihedral angles between the pyrimidine and benzene rings are 42.77 (6) and 46.55 (7)°. In the crystal, N-H⋯O hydrogen bonds connect anions and cations into chains along [010]. Within these chains, R 2 (2)(8) ring motifs are formed by inversion-related barbiturate anions. The H atoms of the partial occupancy water mol-ecule were not located nor included in the refinement.