5-[1-(1,3-Dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl)-2-oxopropyl]-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione

The title compound, C15H18N4O7, is a product of the substitution reaction of 5,5-dibromo-1,3-dimethylbarbituric acid with sodium sulfide in aqueous acetone. In the crystal, molecules display neither intermolecular nor intramolecular hydrogen bonding and the two barbiturate rings adopt the keto form.

The title compound, C 15 H 18 N 4 O 7 , is a product of the substitution reaction of 5,5-dibromo-1,3-dimethylbarbituric acid with sodium sulfide in aqueous acetone. In the crystal, molecules display neither intermolecular nor intramolecular hydrogen bonding and the two barbiturate rings adopt the keto form.

Experimental
KS gratefully acknowledges financial support from the Deanship of Scientific Research at the University of Jordan.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: MW2109).

Kamal Sweidan and Manfred Steimann Comment
Many 1,3-dimethylbarbituric acid derivatives play important roles in the areas of pharmaceutical and medicinal chemistry (Bojarski et al., 1985;Sans & Chosaz, 1988). In the target molecule, two moieties of the 1,3-dimethylbarbiturate anion were attached to the same carbon of the acetone molecule and hydrogen sulfide and sodium bromide were produced during the course of the reaction. It is clear that each barbiturate ring adopts a keto form rather than the enol form as

Experimental
The title compound, C 15 H 18 N 4 O 7 , was prepared by addition of a solution of 5,5-dibromo-1,3-dimethylbarbituric acid (Sweidan et al., 2010), (0.74g, 2.4 mmol) in 10 mL of acetone to a solution of sodium sulfide (0.19g, 2.4 mmol) in 15 mL of water at room temperature. After the reaction mixture was stirred overnight, the precipitate was filtered off and dried in vacuo. The yield after recrystallisation from dichloromethane/diethyl ether was 0.24g (22%) as colorless crystals.

Refinement
Hydrogen atoms were included in the refinement at calculated positions C-H = 0.95-1.00 Å and with U iso (H) = 1.2U eq (aromatic C) or 1.5U eq (aliphatic C), using a riding-model approximation.

5-[1-(1,3-Dimethyl-2,4,6-trioxohexahydropyrimidin-5-yl)-2-oxopropyl]-1,3-
dimethylpyrimidine-2,4,6(1H,3H,5H)-trione where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.17 e Å −3 Δρ min = −0.17 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.