Ethane-1,2-diaminium bis(4-carboxy-2-propyl-1H-imidazole-5-carboxyate) monohydrate

In the title hydrated molecular salt, C2H10N2 2+·2C8H9N2O4 −·H2O, an intramolecular O—H⋯O hydrogen bond occurs in the anion, forming an S(7) ring. The –CO2 and –CO2H groups make dihedral angles of 3.2 (2) and 2.0 (3)°, respectively, with the five-membered ring. In the crystal, N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds lead to the formation of a three-dimensional supramolecular architecture. The methyl group in the anion is disordered over two sets of sites in a 0.716 (9):0.284 (9) ratio. The ethylenediamine cation is generated by symmetry and the water molecule lies on a twofold axis.

In the title hydrated molecular salt, C 2 H 10 N 2 2+ Á2C 8 H 9 N 2 O 4 À Á-H 2 O, an intramolecular O-HÁ Á ÁO hydrogen bond occurs in the anion, forming an S(7) ring. The -CO 2 and -CO 2 H groups make dihedral angles of 3.2 (2) and 2.0 (3) , respectively, with the five-membered ring. In the crystal, N-HÁ Á ÁO, N-HÁ Á ÁN and O-HÁ Á ÁO hydrogen bonds lead to the formation of a three-dimensional supramolecular architecture. The methyl group in the anion is disordered over two sets of sites in a 0.716 (9):0.284 (9) ratio. The ethylenediamine cation is generated by symmetry and the water molecule lies on a twofold axis.
In the crystal structure, intra-molecular hydrogen bonds are present, with O2-H2 acting as a hydrogen bond donor, and O3 atom as a hydrogen bond acceptor, thereby constructing S(7) rings. In addition, the diprotonated ethylenediaminium cations and 2-propyl-1H-imidazole-4-carboxylic acid-5-carboxyate anions together with water molecules are further linked into a three-dimensional supramolecular framework by multiple N-H···O, N-H···N and O-H···O hydrogen bonds ( Fig. 2 and Table 1).

Experimental
All reagents were commercially available and of analytical grade. The mixture of DyCl 3 .6H 2 O (0.189 g, 0.50 mmol), 2propyl-1H-imidazole-4,5-dicarboxylic acid (0.197 g, 1.00 mmol), and ethylenediamine (1 ml) was dissolved in 50 ml H 2 O, and the mixture was stirred and heated to reflux at 80°C for two hours. The resulting solution was filtered, the filtrate was adjusted to pH = 7.5 using 4 M HCl solution, then was placed inside a programmable electric furnace at 130 °C for five days. After cooling the autoclave to room temperature, colorless block crystals of (I) were obtained.

Refinement
H atoms were treated as riding, with C-H distances of 0.96 Å for methyl, 0.97 Å for methylene, N-H distances in the range of 0.96-0.89 Å and O-H distances of 0.82 Å for hydroxy group and 0.84 Å for water, and were refined as riding with U iso (H)=1.2U eq (C methylene , O2 and N) and U iso (H)=1.5U eq (O1W and (C methyl )).

Figure 1
The molecular structure of (I), with displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level.  Three-dimensional structure of (I), with H-bonds indicated by dashed lines. Displacement ellipsoids for the non-hydrogen atoms are drawn at the 50% probability level. 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 > σ(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.