3,5-Dimethylpyrazolium 3,5-dinitrosalicylate

In the title molecular salt, C5H9N2 +·C7H3N2O7 −, the roughly planar anion (r.m.s. deviation = 0.120 Å) has been deprotonated at the phenol group. An intramolecular O—H⋯O hydrogen bond in the anion generates an S(6) ring. In the crystal, the components are linked by cation-to-anion N—H⋯O and N—H⋯(O,O) hydrogen bonds, generating [010] double chains. Weak C—H⋯O interactions consolidate the packing.

In this case ( Fig. 1) it is the phenol H that has been deprotonated. The C-O distance 1.284 (4) Å concerning the phenolate is similar to the proton transfer compound bearing the 3,5-dinitrosalicylate in which only the phenol group has One anion is bonded to one cation via N-H···O, and CH 3 -O associations to form a heteroadduct.
For the presence of these interactions, there are close joint motifs with descriptors of R 2 1(6), and R 1 2(6). The usual intramolecular hydrogen bond is found between the phenolate and the carboxyl group to exhibit a S 1 1(6) graph. The heteroadducts were linked together by the CH 3 -O association between the methyl group of the pyrazole and the 5-nitro group with C-O distance of 3.415 Å to form one-dimensional chain running along the direction that made an angle of ca 60° with the a axis (Fig. 2). The chains were further stacked along the direction that is perpendicular with its extending direction via the interchain N-π interaction between the 5-nitro group and the phenyl ring of the anion with N-Cg distance of 3.236 Å to form two-dimensional sheet extending parallel to the ab plane. The sheets were further stacked along the c axis direction by the CH-O, N-H···O, and O-H···O associations to form three-dimensional ABAB layer network structure. Herein the chains at adjacent layers intersect at an angle of ca 120° with each other.

Experimental
A solution of 3,5-dimethyl pyrazole (19.2 mg, 0.2 mmol) in 5 ml of MeOH was added to a MeOH solution (6 ml) containing 3,5-dinitrosalicylic acid (22.8 mg, 0.1 mmol) under continuous stirring. The solution was stirred for about 1 h at room temperature, then the solution was filtered into a test tube. The solution was left standing at room temperature for several days, yellow blocks were isolated after slow evaporation of the solution in air at ambient temperature. The crystals were collected and dried in air to give the title compound.

Refinement
The absolute structure could not be determined in the present refinement. Hydrogen atoms attached to the C atoms were

Figure 1
The structure of the title compound, showing displacement ellipsoids drawn at the 30% probability level.

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.