2,6-Diamino-4-chloropyrimidinium 4-carboxybutanoate

In the title molecular salt, C4H6ClN4 +·C5H7O4 −, the cation is essentially planar, with a maximum deviation of 0.037 (1) Å for all non-H atoms. The anions are self-assembled through O—H⋯O hydrogen bonds, forming a supramolecular zigzag chain with graph-set notation C(8). In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms of the anion via a pair of N—H⋯O hydrogen bonds with an R 2 2(8) ring motif. This motif further self-organizes through N—H⋯O and O—H⋯O hydrogen bonds, generating an array of six hydrogen bonds, the rings having graph-set notation R 3 2(8), R 2 2(8), R 4 2(8), R 2 2(8) and R 3 2(8). In addition, another type of R 2 2(8) motif is formed by inversion-related pyrimidinium cations via N—H⋯N hydrogen bonds, forming a two-dimensional network parallel to (101).

In the title molecular salt, C 4 H 6 ClN 4 + ÁC 5 H 7 O 4 À , the cation is essentially planar, with a maximum deviation of 0.037 (1) Å for all non-H atoms. The anions are self-assembled through O-HÁ Á ÁO hydrogen bonds, forming a supramolecular zigzag chain with graph-set notation C(8). In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms of the anion via a pair of N-HÁ Á ÁO hydrogen bonds with an R 2 2 (8) ring motif. This motif further self-organizes through N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds, generating an array of six hydrogen bonds, the rings having graph-set notation R 3 2 (8), R 2 2 (8), R 4 2 (8), R 2 2 (8) and R 3 2 (8). In addition, another type of R 2 2 (8) motif is formed by inversion-related pyrimidinium cations via N-HÁ Á ÁN hydrogen bonds, forming a two-dimensional network parallel to (101).

Experimental
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 Pyrimidine derivatives are very important molecules in biology and have many application in the areas of pesticide and pharmaceutical agents (Condon et al., 1993). For example, imazosulfuron, ethirmol and mepanipyrim have been commercialized as agrochemicals (Maeno et al., 1990). Pyrimidine derivatives have also been developed as antiviral agents, such as AZT, which is the most widely-used anti-AIDS drug (Gilchrist, 1997). Glutaric acid (pentanedioic acid) is a dicarboxylic acid with five carbon atoms, occurring in plant and animal tissues. Glutaric acid is found in the blood and urine. It is used in the synthesis of phamaceuticals, surfactants and metal finishing compounds. Alpha-ketoglutaic acid is used in dietary supplements to improve protein synthesis (Windholz, 1976). The related crystal structures of Bis(2,6-diamino-4-chloropyrimidin-1-ium) fumarate (Thanigaimani et al., 2012a) and 2,6-diamno-4-chloropyrimidine-benzoic acid (1/1) (Thanigaimani et al., 2012b) have been recently reported. In order to study some interesting hydrogen bonding interactions, the crystal structure determination of the title compound, (I), was carried out.

Experimental
Hot methanol solutions (20 ml) of 2,6-diamino-4-chloropyrimidine (36 mg, Aldrich) and glutaric acid (33 mg, Merck) were mixed and warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound (I) appeared after a few days.

Refinement
O-and N-bound H atoms were located in a difference Fourier maps and allowed to be refined freely were refined using a riding model, with U iso (H)=1.2 U eq (C).

Figure 1
The molecular structure of the title compound with atom labels with 50% probability displacement ellipsoids.  Carboxyl-carboxylate interactions made up of hydrogen glutarate anion

Figure 3
The crystal packing of (I), showing hydrogen-bonded (dashed lines) two-dimensional networks parallel to the bc-plane.
The H atoms not involved in the intermolecular interactions have been omitted for clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.24 e Å −3 Δρ min = −0.27 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.