Bis(2-methylimidazolium) chloranilate

The asymmetric unit of the title structure, 2C4H7N2 +·C6Cl2O4 2−, consists of one 2-methylimidazolium cation and one-half of a chloranilate anion, the formula unit being generated by crystallographic inversion symmetry. N—H⋯O hydrogen bonds link the ions into a two-dimensional framework parallel to the (102) plane. No π–π stacking or C—H⋯π interactions are observed in the crystal structure.

The asymmetric unit of the title structure, 2C 4 H 7 N 2 + Á-C 6 Cl 2 O 4 2À , consists of one 2-methylimidazolium cation and one-half of a chloranilate anion, the formula unit being generated by crystallographic inversion symmetry. N-HÁ Á ÁO hydrogen bonds link the ions into a two-dimensional framework parallel to the (102) plane. Nostacking or C-HÁ Á Á interactions are observed in the crystal structure.
The asymmetric unit contains one 2-methylimidazolium cation, half of a chloranilate anion the formula unit being generated by crystallogrphic inversion symmetry ( Fig. 1). A proton has been transferred from the hydroxyl group in CA to the 2-MeIm N atom, forming the 1:2 organic salt.
In the crystal structure, by a combination of three N-H···O hydrogen bonds (Table 1) the molecules are linked into a two-dimensional framework ( Fig. 2) built from the R 2 1 (5) and R 6 8 (32) rings (Bernstein et al., 1995) running parallel to the (102) plane. Two such networks pass through the cell and analysis using PLATON (Spek, 2003) shows that there are no direction-specific interactions such as π-π and C-H···π interactions observed in the packing of the structure.

S2. Experimental
All the reagents and solvents were used as obtained without further purification. Equivalent molar amount of CA (0.2 mmol, 41.4 mg), 2-MeIm (0.2 mmol, 16.2 mg) and Cu(NO 3 ) 2 .3(H 2 O)(0.2 mmol, 48 mg) in 10 ml water solvent sealed in a 25 ml Teflon-lined autoclave. The mixture was heated to 393 K and maintained for 48 h. After slowly cooling to room temperature with the rate of 5°/h, dark red crystals suitable for single-crystal X-ray diffraction analysis were obtained.
The crystals were filtered and washed with distilled water and dried in air.

S3. Refinement
H atoms bonded to carbon atoms were located at the geometrical positions [C-H = 0.96 Å (methyl) or 0.93 Å (aromatic), and U iso (H) = 1.5U eq (methyl) or 1.2U eq (aromatic). H atoms attached to N atoms were located in difference fourier maps and N-H distance refined freely and their U iso values set 1.2 times of their carrier atoms.   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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.9935 (