Ethyl 2-[(carbamoylamino)imino]propanoate hemihydrate

The title compound, C6H11N3O3·0.5H2O, has two independent molecules and one molecule of water in the asymmetric unit. The crystal packing is stabilized by intermolecular N—H⋯N, O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds. These interactions form a two-dimensional array in the ab plane with a zigzag motif which has an angle close to 35° between the zigzag planes. The hydrogen bonding can be best described using the graph-set notation as N 1 = C(10)R 2 2(10)R 2 2(8) and N 2 = R 6 4(20)R 2 2(8).

The title compound, C 6 H 11 N 3 O 3 Á0.5H 2 O, has two independent molecules and one molecule of water in the asymmetric unit. The crystal packing is stabilized by intermolecular N-HÁ Á ÁN, O-HÁ Á ÁO, N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds. These interactions form a two-dimensional array in the ab plane with a zigzag motif which has an angle close to 35 between the zigzag planes. The hydrogen bonding can be best described using the graph-set notation as N 1 = C(10)R 2 2 (10)R 2 2 (8) and N 2 = R 6 4 (20)R 2 2 (8).

Experimental
Crystal data H atoms treated by a mixture of independent and constrained refinement Á max = 0.20 e Å À3 Á min = À0.18 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).    (Dimmock,1993); the aryl semicarbazone 4-bromobenzaldehyde semicarbazone has been a standard anticonvulsant drug selected by the National Institutes of Health, USA. They can also be used as drugs for Chagas's disease (Cerecetto, 2000) as well as hypnotic, pesticide and herbicide uses (Armor, 1992). The synthesis of ethyl pyruvate semicarbazone (spe) (Scheme I) was reported more than 60 years (Kulka, 1946); but to date the structure determination has not been reported. This structure will permit further study of the metal coordination properties of these interesting ligands.  Figure 2 and using the graph-set notation the system can be best described as N 1 =C(10)R 2 2 (10)R 2 2 (8) and N 2 =R 6 4 (20)R 2 2 (8) (Etter, 1990).
There are two isomeric forms for compounds derived from ethyl pyruvate semicarbazone namely the E and Z isomers.
The present structure is clearly the E form, Figures 1 and 2. The molecules of spe form a two-dimensional array in the ab plane with a zigzag motif which has an angle close to 35° between the zigzag planes.
supplementary materials sup-2 Refinement C-bound H atoms were included using the riding model approximation with C-H = 0.95 Å, with a common U_iso_(H).
The H atoms of the water molecule were located from an electron density map, fixed in these positions and assigned the same isotropic displacement as the other H atoms.