Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807043826/lh2493sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807043826/lh2493Isup2.hkl |
CCDC reference: 663751
Key indicators
- Single-crystal X-ray study
- T = 294 K
- Mean (C-C) = 0.003 Å
- R factor = 0.056
- wR factor = 0.169
- Data-to-parameter ratio = 13.9
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT213_ALERT_2_C Atom O5 has ADP max/min Ratio ............. 3.20 prola PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for S1 PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.92
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
For related literature, see: Fan et al. (2005); Hou (2007); Muthiah et al. (2003); Smith (2005); Smith et al. (2004, 2005a, 2005b); Smith, Wermuth & Healy (2005, 2006); Wang & Wei (2007).
Crystals of the title compound were unexpectedly obtained by mixing equimolar amount of 5-sulfosalicylic acid dihydrate (0.1 mmol, 25.4 mg), imidazole (0.1 mmol, 6.8 mg) and silver nitrate (0.1 mmol, 17.0 mg) in 10 ml water solvent sealed in a 25 ml Teflon-lined autoclave. The mixture was heated to 423 K and maintained for 140 h. After slowly cooling to room temperature with the rate of 10°/h, colorless crystals suitable for single-crystal X-ray diffraction analysis were obtained. The crystals were filtered and washed with distilled water and dried in air (Yield: 40%, 13.0 mg, based on the 1:1 organic salt.)
H atoms bonded to carbon atoms were located at the geometrical positions with C—H=0.93 Å, and Uiso(H) = 1.2Ueq(C). H atoms attached to N and O atoms were located from the difference maps with the N–H and O–H distances refined freely and their Uiso values set 1.5 or 1.2 times of their carrier atoms, respectively.
5-sulfosalicylic acid (5-SSA) is a strong organic acid which can readily release its sulfonic proton when reacting with many Lewis bases. The crystals structures of a series of 5-SSA organic salts have been reported (Smith et al., 2004; Smith et al., 2005a,b; Smith, Wermuth & Healy, 2005; Smith, 2005; Smith et al., 2006; Muthiah et al., 2003; Fan, et al., 2005). More recently, two organic salts formed by 5-SSA and benzimidazole and 4-Methylimidazole have been reported (Wang & Wei, 2007; Hou, 2007). To further the research of analogous 5-SSA-containing organic adducts, we report here the crystal structure of imidazolium 3-carboxy-4-hydroxybenzenesulfonate (abbr. 5-SSA·Im).
The asymmetric unit consists of one imidazolium cation, one sulfosalicylate anion (Fig. 1). The sulfonic hydrogen atom has been transferred to the imine N atom. Unlike the reported analogs (Hou, 2007; Wang & Wei, 2007), in the title structure there are no solvent molecules in the crystal lattice. In the supramolecular structure, by a combination of N–H···O, O–H···O and C–H···O hydrogen bonds and π-π stacking interactions the ions are linked into a three-dimensional framework which can be easily discussed in terms of two types of simple substructures.
Firstly, by means of the series of H-bond interactions listed in table 1, 5-SSA anions and imidazole (abbr. Im) cations are interlinked into a two-dimensional network running parallel to the (101) direction (Fig.2). In addition to H-bonds interactions, the (101) network is consolidated by two intra-network π–π stacking interactions [Cg1···Cg1vii = 4.075 (2) Å and Cg2···Cg2ix = 3.655 (2) Å, symmetry code: (vii) 1 - x, 1 - y, 1 - z; (ix) 1 - x, 2 - y, 1 - z where Cg1 and Cg2 are the centroids of the benzene and imidzole rings.]
Secondly, by the other two symmetry-related π-π stacking interactions between the adjacent network [Cg1···Cg1vi = 3.874 (2) Å and Cg2···Cg2viii = 3.774 (2) Å, symmetry code: (vi) -x, 1 - y, 1 - z; (viii) -x, 2 - y, 1 - z, where Cg1 and Cg2 are the centroids of the benzene and imidzole rings] the adjacent two-dimensional networks are interlinked into a three-dimensional network (Fig.3). It is noteworthy that in the supramolecular structure of the title compound the 5-SSA anions and Im cations are stacked homogeneously, i.e. 5-SSA anions stack only on top of 5-SSA anions, and Im anions stack only on top of Im anion. However, the stacks in the 4-Methyl dihydrate and benzimidazole trihydrate analogs reported by (Hou, 2007; Wang & Wei, 2007) are heterogeneous and homogeneous, respectively. Why and how the cations and water solvent molecules affect the stacking patterns is worthy of further study.
For related literature, see: Fan et al. (2005); Hou (2007); Muthiah et al. (2003); Smith (2005); Smith et al. (2004, 2005a, 2005b); Smith, Wermuth & Healy (2005, 2006); Wang & Wei (2007).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).
C3H5N2+·C7H5O6S− | F(000) = 592 |
Mr = 286.26 | Dx = 1.606 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 2471 reflections |
a = 6.9486 (5) Å | θ = 2.2–24.7° |
b = 14.5898 (11) Å | µ = 0.30 mm−1 |
c = 12.0504 (9) Å | T = 294 K |
β = 104.220 (1)° | Block, colorless |
V = 1184.22 (15) Å3 | 0.10 × 0.10 × 0.08 mm |
Z = 4 |
Bruker SMART APEX CCD area-detector diffractometer | 2575 independent reflections |
Radiation source: fine focus sealed Siemens Mo tube | 1805 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.049 |
0.3° wide ω exposures scans | θmax = 27.0°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −8→8 |
Tmin = 0.969, Tmax = 0.971 | k = −18→18 |
12957 measured reflections | l = −15→15 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.169 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | w = 1/[σ2(Fo2) + (0.1041P)2] where P = (Fo2 + 2Fc2)/3 |
2575 reflections | (Δ/σ)max < 0.001 |
185 parameters | Δρmax = 0.65 e Å−3 |
0 restraints | Δρmin = −0.41 e Å−3 |
C3H5N2+·C7H5O6S− | V = 1184.22 (15) Å3 |
Mr = 286.26 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.9486 (5) Å | µ = 0.30 mm−1 |
b = 14.5898 (11) Å | T = 294 K |
c = 12.0504 (9) Å | 0.10 × 0.10 × 0.08 mm |
β = 104.220 (1)° |
Bruker SMART APEX CCD area-detector diffractometer | 2575 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1805 reflections with I > 2σ(I) |
Tmin = 0.969, Tmax = 0.971 | Rint = 0.049 |
12957 measured reflections |
R[F2 > 2σ(F2)] = 0.057 | 0 restraints |
wR(F2) = 0.169 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.07 | Δρmax = 0.65 e Å−3 |
2575 reflections | Δρmin = −0.41 e Å−3 |
185 parameters |
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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.2333 (3) | 0.47417 (16) | 0.47446 (19) | 0.0266 (5) | |
C2 | 0.3081 (4) | 0.49675 (17) | 0.58992 (19) | 0.0305 (6) | |
C3 | 0.3199 (4) | 0.58790 (17) | 0.6234 (2) | 0.0339 (6) | |
H3 | 0.3695 | 0.6029 | 0.7001 | 0.041* | |
C4 | 0.2586 (4) | 0.65660 (17) | 0.5438 (2) | 0.0334 (6) | |
H4 | 0.2680 | 0.7176 | 0.5668 | 0.040* | |
C5 | 0.1832 (4) | 0.63454 (16) | 0.42953 (19) | 0.0299 (6) | |
C6 | 0.1715 (4) | 0.54408 (15) | 0.39553 (19) | 0.0285 (6) | |
H6 | 0.1216 | 0.5297 | 0.3187 | 0.034* | |
C7 | 0.2281 (4) | 0.37808 (16) | 0.4350 (2) | 0.0311 (6) | |
C8 | 0.2003 (5) | 1.0567 (2) | 0.4116 (3) | 0.0465 (7) | |
H8 | 0.1535 | 1.0663 | 0.3333 | 0.056* | |
C9 | 0.2919 (4) | 0.9900 (2) | 0.5773 (3) | 0.0513 (8) | |
H9 | 0.3198 | 0.9449 | 0.6336 | 0.062* | |
C10 | 0.3176 (5) | 1.0799 (2) | 0.5933 (3) | 0.0539 (8) | |
H10 | 0.3656 | 1.1096 | 0.6629 | 0.065* | |
N1 | 0.2177 (4) | 0.97671 (16) | 0.4640 (2) | 0.0453 (6) | |
H1A | 0.188 (5) | 0.928 (3) | 0.422 (3) | 0.068* | |
N2 | 0.2606 (4) | 1.11996 (17) | 0.4891 (2) | 0.0486 (7) | |
H2A | 0.266 (5) | 1.180 (3) | 0.477 (3) | 0.073* | |
O1 | 0.2791 (3) | 0.31374 (12) | 0.50053 (15) | 0.0416 (5) | |
O2 | 0.1645 (3) | 0.36856 (13) | 0.32466 (15) | 0.0464 (6) | |
H2B | 0.192 (5) | 0.319 (3) | 0.292 (3) | 0.070* | |
O3 | 0.3731 (3) | 0.43343 (14) | 0.67244 (14) | 0.0444 (6) | |
H3A | 0.350 (5) | 0.385 (3) | 0.632 (3) | 0.067* | |
O4 | 0.1132 (4) | 0.80550 (13) | 0.38169 (18) | 0.0608 (7) | |
O5 | 0.2646 (5) | 0.71675 (13) | 0.2598 (2) | 0.0731 (8) | |
O6 | −0.0765 (4) | 0.69516 (18) | 0.2535 (2) | 0.0870 (10) | |
S1 | 0.11344 (12) | 0.72006 (4) | 0.32363 (5) | 0.0403 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0296 (14) | 0.0194 (12) | 0.0319 (12) | −0.0017 (10) | 0.0096 (10) | −0.0019 (9) |
C2 | 0.0358 (15) | 0.0234 (12) | 0.0314 (12) | −0.0011 (10) | 0.0066 (10) | 0.0029 (9) |
C3 | 0.0442 (16) | 0.0252 (13) | 0.0318 (12) | −0.0033 (11) | 0.0080 (11) | −0.0056 (10) |
C4 | 0.0459 (17) | 0.0190 (12) | 0.0353 (12) | −0.0037 (11) | 0.0100 (11) | −0.0048 (9) |
C5 | 0.0375 (15) | 0.0194 (12) | 0.0337 (12) | −0.0016 (10) | 0.0103 (11) | 0.0007 (9) |
C6 | 0.0388 (15) | 0.0195 (12) | 0.0262 (11) | −0.0008 (10) | 0.0057 (10) | −0.0007 (8) |
C7 | 0.0373 (15) | 0.0212 (12) | 0.0352 (13) | 0.0032 (10) | 0.0099 (11) | −0.0005 (9) |
C8 | 0.059 (2) | 0.0361 (16) | 0.0417 (15) | −0.0014 (14) | 0.0069 (14) | 0.0025 (11) |
C9 | 0.050 (2) | 0.0452 (18) | 0.0535 (17) | 0.0016 (14) | 0.0026 (14) | 0.0190 (14) |
C10 | 0.058 (2) | 0.051 (2) | 0.0468 (16) | −0.0051 (16) | 0.0030 (15) | −0.0055 (14) |
N1 | 0.0522 (16) | 0.0236 (12) | 0.0595 (15) | −0.0015 (11) | 0.0125 (12) | −0.0062 (10) |
N2 | 0.0590 (17) | 0.0211 (12) | 0.0619 (16) | −0.0022 (11) | 0.0073 (13) | 0.0006 (10) |
O1 | 0.0604 (14) | 0.0190 (9) | 0.0433 (11) | 0.0023 (8) | 0.0088 (9) | 0.0015 (7) |
O2 | 0.0721 (15) | 0.0243 (10) | 0.0373 (11) | 0.0076 (9) | 0.0030 (10) | −0.0081 (7) |
O3 | 0.0688 (15) | 0.0251 (10) | 0.0329 (10) | 0.0013 (9) | 0.0000 (10) | 0.0044 (7) |
O4 | 0.110 (2) | 0.0157 (9) | 0.0564 (13) | 0.0093 (11) | 0.0199 (13) | −0.0023 (8) |
O5 | 0.136 (2) | 0.0249 (11) | 0.0788 (16) | 0.0221 (12) | 0.0651 (16) | 0.0256 (10) |
O6 | 0.104 (2) | 0.0504 (16) | 0.0761 (16) | −0.0188 (13) | −0.0361 (16) | 0.0301 (12) |
S1 | 0.0679 (6) | 0.0144 (4) | 0.0370 (4) | −0.0005 (3) | 0.0100 (3) | 0.0037 (2) |
C1—C6 | 1.389 (3) | C8—N1 | 1.318 (4) |
C1—C2 | 1.400 (3) | C8—H8 | 0.9300 |
C1—C7 | 1.478 (3) | C9—C10 | 1.332 (5) |
C2—O3 | 1.351 (3) | C9—N1 | 1.350 (4) |
C2—C3 | 1.386 (3) | C9—H9 | 0.9300 |
C3—C4 | 1.380 (3) | C10—N2 | 1.353 (4) |
C3—H3 | 0.9300 | C10—H10 | 0.9300 |
C4—C5 | 1.386 (3) | N1—H1A | 0.87 (4) |
C4—H4 | 0.9300 | N2—H2A | 0.89 (4) |
C5—C6 | 1.378 (3) | O2—H2B | 0.87 (4) |
C5—S1 | 1.765 (2) | O3—H3A | 0.86 (4) |
C6—H6 | 0.9300 | O4—S1 | 1.4296 (19) |
C7—O1 | 1.222 (3) | O5—S1 | 1.447 (3) |
C7—O2 | 1.301 (3) | O6—S1 | 1.428 (3) |
C8—N2 | 1.307 (4) | ||
C6—C1—C2 | 119.0 (2) | N2—C8—H8 | 126.1 |
C6—C1—C7 | 119.8 (2) | N1—C8—H8 | 126.1 |
C2—C1—C7 | 121.1 (2) | C10—C9—N1 | 107.0 (3) |
O3—C2—C3 | 117.2 (2) | C10—C9—H9 | 126.5 |
O3—C2—C1 | 123.1 (2) | N1—C9—H9 | 126.5 |
C3—C2—C1 | 119.7 (2) | C9—C10—N2 | 107.0 (3) |
C4—C3—C2 | 120.5 (2) | C9—C10—H10 | 126.5 |
C4—C3—H3 | 119.7 | N2—C10—H10 | 126.5 |
C2—C3—H3 | 119.7 | C8—N1—C9 | 109.0 (3) |
C3—C4—C5 | 119.9 (2) | C8—N1—H1A | 118 (2) |
C3—C4—H4 | 120.0 | C9—N1—H1A | 133 (2) |
C5—C4—H4 | 120.0 | C8—N2—C10 | 109.1 (3) |
C6—C5—C4 | 119.9 (2) | C8—N2—H2A | 126 (2) |
C6—C5—S1 | 118.44 (17) | C10—N2—H2A | 124 (2) |
C4—C5—S1 | 121.59 (19) | C7—O2—H2B | 120 (2) |
C5—C6—C1 | 120.9 (2) | C2—O3—H3A | 100 (2) |
C5—C6—H6 | 119.5 | O6—S1—O4 | 113.53 (17) |
C1—C6—H6 | 119.5 | O6—S1—O5 | 111.29 (19) |
O1—C7—O2 | 123.4 (2) | O4—S1—O5 | 112.18 (14) |
O1—C7—C1 | 122.7 (2) | O6—S1—C5 | 107.30 (13) |
O2—C7—C1 | 113.9 (2) | O4—S1—C5 | 107.19 (12) |
N2—C8—N1 | 107.9 (3) | O5—S1—C5 | 104.74 (12) |
C6—C1—C2—O3 | −179.4 (2) | C2—C1—C7—O1 | 3.5 (4) |
C7—C1—C2—O3 | −2.3 (4) | C6—C1—C7—O2 | 0.6 (3) |
C6—C1—C2—C3 | −0.2 (4) | C2—C1—C7—O2 | −176.5 (2) |
C7—C1—C2—C3 | 176.9 (2) | N1—C9—C10—N2 | −0.7 (4) |
O3—C2—C3—C4 | 179.2 (2) | N2—C8—N1—C9 | −0.4 (4) |
C1—C2—C3—C4 | 0.0 (4) | C10—C9—N1—C8 | 0.7 (4) |
C2—C3—C4—C5 | 0.5 (4) | N1—C8—N2—C10 | −0.1 (4) |
C3—C4—C5—C6 | −0.7 (4) | C9—C10—N2—C8 | 0.5 (4) |
C3—C4—C5—S1 | −177.1 (2) | C6—C5—S1—O6 | 50.0 (3) |
C4—C5—C6—C1 | 0.4 (4) | C4—C5—S1—O6 | −133.5 (3) |
S1—C5—C6—C1 | 176.93 (19) | C6—C5—S1—O4 | 172.3 (2) |
C2—C1—C6—C5 | 0.0 (4) | C4—C5—S1—O4 | −11.3 (3) |
C7—C1—C6—C5 | −177.1 (2) | C6—C5—S1—O5 | −68.3 (2) |
C6—C1—C7—O1 | −179.4 (2) | C4—C5—S1—O5 | 108.1 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O1 | 0.86 (4) | 1.85 (4) | 2.665 (3) | 158 (3) |
N1—H1A···O4 | 0.87 (4) | 1.89 (4) | 2.720 (3) | 159 (3) |
C8—H8···O3i | 0.93 | 2.39 | 3.206 (4) | 147 |
C8—H8···O5ii | 0.93 | 2.59 | 3.167 (4) | 121 |
C4—H4···O4 | 0.93 | 2.57 | 2.930 (3) | 104 |
C6—H6···O2 | 0.93 | 2.37 | 2.696 (3) | 100 |
C10—H10···O2iii | 0.93 | 2.49 | 3.293 (4) | 144 |
C9—H9···O6iii | 0.93 | 2.50 | 3.419 (4) | 168 |
C4—H4···O6iii | 0.93 | 2.58 | 3.310 (3) | 136 |
O2—H2B···O5iv | 0.87 (4) | 1.67 (4) | 2.536 (3) | 174 (4) |
N2—H2A···O1v | 0.89 (4) | 1.97 (4) | 2.832 (3) | 162 (3) |
Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) x+1/2, −y+3/2, z+1/2; (iv) −x+1/2, y−1/2, −z+1/2; (v) x, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C3H5N2+·C7H5O6S− |
Mr | 286.26 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 294 |
a, b, c (Å) | 6.9486 (5), 14.5898 (11), 12.0504 (9) |
β (°) | 104.220 (1) |
V (Å3) | 1184.22 (15) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.30 |
Crystal size (mm) | 0.10 × 0.10 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.969, 0.971 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12957, 2575, 1805 |
Rint | 0.049 |
(sin θ/λ)max (Å−1) | 0.639 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.169, 1.07 |
No. of reflections | 2575 |
No. of parameters | 185 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.65, −0.41 |
Computer programs: SMART (Bruker, 2001), SAINT-Plus (Bruker, 2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3A···O1 | 0.86 (4) | 1.85 (4) | 2.665 (3) | 158 (3) |
N1—H1A···O4 | 0.87 (4) | 1.89 (4) | 2.720 (3) | 159 (3) |
C8—H8···O3i | 0.93 | 2.39 | 3.206 (4) | 147 |
C8—H8···O5ii | 0.93 | 2.59 | 3.167 (4) | 121 |
C4—H4···O4 | 0.93 | 2.57 | 2.930 (3) | 104 |
C6—H6···O2 | 0.93 | 2.37 | 2.696 (3) | 100 |
C10—H10···O2iii | 0.93 | 2.49 | 3.293 (4) | 144 |
C9—H9···O6iii | 0.93 | 2.50 | 3.419 (4) | 168 |
C4—H4···O6iii | 0.93 | 2.58 | 3.310 (3) | 136 |
O2—H2B···O5iv | 0.87 (4) | 1.67 (4) | 2.536 (3) | 174 (4) |
N2—H2A···O1v | 0.89 (4) | 1.97 (4) | 2.832 (3) | 162 (3) |
Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x+1/2, y+1/2, −z+1/2; (iii) x+1/2, −y+3/2, z+1/2; (iv) −x+1/2, y−1/2, −z+1/2; (v) x, y+1, z. |
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5-sulfosalicylic acid (5-SSA) is a strong organic acid which can readily release its sulfonic proton when reacting with many Lewis bases. The crystals structures of a series of 5-SSA organic salts have been reported (Smith et al., 2004; Smith et al., 2005a,b; Smith, Wermuth & Healy, 2005; Smith, 2005; Smith et al., 2006; Muthiah et al., 2003; Fan, et al., 2005). More recently, two organic salts formed by 5-SSA and benzimidazole and 4-Methylimidazole have been reported (Wang & Wei, 2007; Hou, 2007). To further the research of analogous 5-SSA-containing organic adducts, we report here the crystal structure of imidazolium 3-carboxy-4-hydroxybenzenesulfonate (abbr. 5-SSA·Im).
The asymmetric unit consists of one imidazolium cation, one sulfosalicylate anion (Fig. 1). The sulfonic hydrogen atom has been transferred to the imine N atom. Unlike the reported analogs (Hou, 2007; Wang & Wei, 2007), in the title structure there are no solvent molecules in the crystal lattice. In the supramolecular structure, by a combination of N–H···O, O–H···O and C–H···O hydrogen bonds and π-π stacking interactions the ions are linked into a three-dimensional framework which can be easily discussed in terms of two types of simple substructures.
Firstly, by means of the series of H-bond interactions listed in table 1, 5-SSA anions and imidazole (abbr. Im) cations are interlinked into a two-dimensional network running parallel to the (101) direction (Fig.2). In addition to H-bonds interactions, the (101) network is consolidated by two intra-network π–π stacking interactions [Cg1···Cg1vii = 4.075 (2) Å and Cg2···Cg2ix = 3.655 (2) Å, symmetry code: (vii) 1 - x, 1 - y, 1 - z; (ix) 1 - x, 2 - y, 1 - z where Cg1 and Cg2 are the centroids of the benzene and imidzole rings.]
Secondly, by the other two symmetry-related π-π stacking interactions between the adjacent network [Cg1···Cg1vi = 3.874 (2) Å and Cg2···Cg2viii = 3.774 (2) Å, symmetry code: (vi) -x, 1 - y, 1 - z; (viii) -x, 2 - y, 1 - z, where Cg1 and Cg2 are the centroids of the benzene and imidzole rings] the adjacent two-dimensional networks are interlinked into a three-dimensional network (Fig.3). It is noteworthy that in the supramolecular structure of the title compound the 5-SSA anions and Im cations are stacked homogeneously, i.e. 5-SSA anions stack only on top of 5-SSA anions, and Im anions stack only on top of Im anion. However, the stacks in the 4-Methyl dihydrate and benzimidazole trihydrate analogs reported by (Hou, 2007; Wang & Wei, 2007) are heterogeneous and homogeneous, respectively. Why and how the cations and water solvent molecules affect the stacking patterns is worthy of further study.