Bis(2-amino-6-methylpyrimidin-1-ium-4-olate-κ2 N 3,O)bis(nitrato-κ2 O,O′)cadmium(II)

In the title compound, [Cd(NO3)2(C5H7N3O)2], the CdII atom is eight-coordinated by two amine N atoms and two O atoms from two zwitterionic, biodentate 2-amino-6-methylpyrimidin-1-ium-4-olate ligands and by four O atoms from two nitrate groups. Intramolecular N—H⋯O hydrogen bonds occur. The crystal packing is stabilized by intermolecular N—H⋯O and C—H⋯O hydrogen bonds, two of which are bifurcated, between the nitrate anions and the organic groups.

In the title compound, [Cd(NO 3 ) 2 (C 5 H 7 N 3 O) 2 ], the Cd II atom is eight-coordinated by two amine N atoms and two O atoms from two zwitterionic, biodentate 2-amino-6-methylpyrimidin-1-ium-4-olate ligands and by four O atoms from two nitrate groups. Intramolecular N-HÁ Á ÁO hydrogen bonds occur. The crystal packing is stabilized by intermolecular N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds, two of which are bifurcated, between the nitrate anions and the organic groups.

Related literature
For common applications of this material, see: Aminabhavi et al. (1986); Ye et al. (2008). For the geometry around the Cd atom, see: Han et al. (2008).
Here we report the synthesis and crystal structure of the title compound Cd(NO 3 ) 2 (C 5 H 7 N 3 O) 2 . In the atomic arrangement of this material, the distorted polyhedral Cd environment contains two nitrate anions and two organic moieties. Each one of them is coordinated in the bidental mode; the Cd II is thus eight coordinated ( Fig.1), with normal bond distances and angles around the cation (Han et al., 2008). The polyhedra are interconnected by a set of N-H···O and C-H···O hydrogen bonds generated by the organic entities ( Table 1). Two of the H-bonds present, N6-H6B···(O2A, O4) and N6A-H6D···(O2, O3), are bifurcated. Fig. 2 shows the results of H-bonding, in the form of undulated columns running along the c axis, laterally interlinked to form a three dimensional infinite network Experimental A solution of Cd(NO 3 ) 2 (0.1 mmol) in ethanol was added dropwise to a solution of 2-Amino-4-hydroxy-6-methylpyrimidine 0.1 mmol in ethanol. After stirring for 30 min, the mixture was filtered. Crystals suitable for X-ray analysis were obtained by evaporating the filtrate at room temperature.

Refinement
All H atoms were located in a difference Fourier synthesis, placed in calculated positions and refined as riding on their parent atoms, using SHELXL97 (Sheldrick, 2008) defaults (N-H: 0.86Å, C-H: 0.93-0.97Å; U iso (H) = 1.2U eq (N,C)). The original structure validation reported that the U values of the coordinating oxygen atoms were too large in relation to the Cd centre, causing the Hirshfeld test to fail. This may be due to mild disorder of the nitrate anions. Restraints on the anisotropic temperature factors (DELU and SIMU instructions in SHELXL97, Sheldrick, 2008) were used to obtain more meaningful anisotropic displacement ellipsoids.

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 > σ(F 2 ) is used only for calculating Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq