Download citation
Download citation
link to html
In the crystal structure of the title compound, C7H7N2+·C7H5O4, the partially overlapped arrangement and the face-to-face separation of 3.557 (7) Å suggest π–π stacking between parallel benzimidazolium cations, and the C—H...Cg angle of 173° and H...Cg separation of 2.64 Å (where Cg is the centroid of the benzene ring) suggest C—H...π stacking between the benzimidazolium cation and dihydroxy­benzoate anion. Classical N—H...O and O—H...O and weak C—H...O hydrogen bonds consolidate the crystal structure.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680504170X/hg6284sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S160053680504170X/hg6284Isup2.hkl
Contains datablock I

CCDC reference: 296574

Key indicators

  • Single-crystal X-ray study
  • T = 295 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.041
  • wR factor = 0.115
  • Data-to-parameter ratio = 15.9

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 1 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 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

Comment top

We have been interested in the nature of aromatic stacking in complexes for several years (Chen et al., 2003; Pan & Xu, 2004; Li et al., 2005) because aromatic stacking is an important intermolecular non-covalent interaction which correlates with electron transfer in some biological systems (Deisenhofer & Michel, 1989). We present here the structure of the title compound, (I), which contains both benzene and benzimidazol aromatic ring systems.

The molecule of (I) consists of a benzimidazolium (bzim) cation and a dihydroxybenzoate (dhba) anion (Fig. 1). The carboxyl group of dhba is coplanar with the benzene ring [dihedral angle 1.05 (9)°]. The smaller difference of 0.025 (2) Å between the C1—O1 and C1—O2 bond distances (Table 1) is consistent with the value of 0.022 (4) Å found in piperazinium bis(3,5-dihydroxybenzoate) (Burchell et al., 2001) and indicates the deprotonation of the carboxyl group.

Approximately symmetric N—C bonds are observed in the protonated bzim cation; the differences between the N1—C8 and N2—C8 bond distances and between the N1—C13 and N2—C14 bond distances are smaller than twice the standard uncertainties (Table 1).

A partially overlapped arrangement is observed between parallel N1-bzim and N1vi-bzim cations [symmetry code: (vi) −x + 1, −y + 1, −z + 1] (Fig. 2). The face-to-face distances of 3.557 (7) Å suggest the existence of ππ stacking. C—H···π stacking is observed between bzim and dhba (Fig. 1), the C10—H10···Cg angle and H···Cg separation being 173° and 2.64 Å, respectively, where Cg is the centroid of the C2v-containing benzene ring [symmetry code: (v) x − 1/2, y − 1/2, −z + 1/2].

Classical N—H···O and O—H···O and weak C—H···O hydrogen bonds occur (Table 2), consolidating the crystal structure of (I).

Experimental top

CdCl2 (1 mmol), 3,5-dihydroxybenzoic acid (2 mmol), benzimidazole (2 mmol) and Na2CO3 (1 mmol) were dissolved in a water/ethanol solution (20 ml, 1:1). The mixture was refluxed for 2 h and filtered after cooling to room temperature. Single crystals of (I) were obtained from the filtrate after 10 d.

Refinement top

Hydroxy H atoms were located in a difference Fourier map and refined as riding in their as found relative positions (Table 2) with Uiso(H) = 1.2Ueq(O). Other H atoms were placed in calculated positions, with C—H = 0.93 Å and N—H = 0.86 Å, and refined as riding with Uiso(H) = 1.2Ueq(carrier).

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with 50% probability displacement ellipsoids (arbitrary spheres for H atoms). The dashed line indicates the hydrogen bond and the dotted line indicates C—H···π stacking. [Symmetry code: (v) x − 1/2, y − 1/2, z + 1/2.]
[Figure 2] Fig. 2. The unit cell packing diagram showing classical hydrogen bonding (dashed lines) and ππ stacking between parallel bzim molecules. [Symmetry code: (vi) −x + 1, −y + 1, −z + 1.]
Benzimidazolium 3,5-dihydroxybenzoate top
Crystal data top
C7H7N2+·C7H5O4F(000) = 1136
Mr = 272.26Dx = 1.429 Mg m3
Orthorhombic, PbcnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2abCell parameters from 19663 reflections
a = 16.297 (4) Åθ = 3.1–27.0°
b = 10.600 (3) ŵ = 0.11 mm1
c = 14.649 (5) ÅT = 295 K
V = 2530.6 (13) Å3Chunk, brown
Z = 80.40 × 0.38 × 0.36 mm
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2435 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.037
Graphite monochromatorθmax = 27.5°, θmin = 3.1°
Detector resolution: 10.00 pixels mm-1h = 2120
ω scansk = 1313
23272 measured reflectionsl = 1919
2901 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.041H-atom parameters constrained
wR(F2) = 0.115 w = 1/[σ2(Fo2) + (0.0603P)2 + 0.6188P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
2901 reflectionsΔρmax = 0.35 e Å3
182 parametersΔρmin = 0.29 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0108 (10)
Crystal data top
C7H7N2+·C7H5O4V = 2530.6 (13) Å3
Mr = 272.26Z = 8
Orthorhombic, PbcnMo Kα radiation
a = 16.297 (4) ŵ = 0.11 mm1
b = 10.600 (3) ÅT = 295 K
c = 14.649 (5) Å0.40 × 0.38 × 0.36 mm
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2435 reflections with I > 2σ(I)
23272 measured reflectionsRint = 0.037
2901 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0410 restraints
wR(F2) = 0.115H-atom parameters constrained
S = 1.09Δρmax = 0.35 e Å3
2901 reflectionsΔρmin = 0.29 e Å3
182 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N10.60250 (7)0.67812 (12)0.38616 (8)0.0372 (3)
H10.65480.68890.38650.045*
N20.47272 (7)0.71952 (11)0.38770 (9)0.0358 (3)
H20.42760.76160.38930.043*
O10.76817 (6)0.68278 (10)0.40383 (6)0.0347 (3)
O20.87168 (6)0.54682 (10)0.39438 (6)0.0361 (3)
O30.69620 (6)0.76955 (10)0.07692 (6)0.0353 (3)
H3A0.70800.78580.01620.042*
O40.91927 (5)0.47395 (9)0.06519 (6)0.0298 (2)
H4A0.90290.46450.00630.036*
C10.81810 (7)0.61482 (12)0.35910 (8)0.0243 (3)
C20.81354 (7)0.61852 (11)0.25632 (8)0.0235 (3)
C30.75700 (7)0.69565 (12)0.21238 (8)0.0258 (3)
H30.72200.74710.24600.031*
C40.75337 (7)0.69490 (12)0.11773 (8)0.0251 (3)
C50.80546 (7)0.61866 (12)0.06714 (8)0.0251 (3)
H50.80130.61660.00380.030*
C60.86403 (7)0.54516 (11)0.11161 (8)0.0236 (3)
C70.86756 (8)0.54453 (12)0.20633 (8)0.0256 (3)
H70.90610.49460.23620.031*
C80.54718 (9)0.76837 (14)0.39056 (10)0.0371 (3)
H80.55890.85400.39500.045*
C90.42092 (9)0.49446 (15)0.37746 (12)0.0448 (4)
H90.36500.51190.37780.054*
C100.45019 (11)0.37333 (16)0.37261 (14)0.0528 (4)
H100.41300.30700.36920.063*
C110.53357 (11)0.34662 (16)0.37268 (14)0.0558 (5)
H110.55050.26290.37000.067*
C120.59154 (10)0.43933 (15)0.37661 (13)0.0480 (4)
H120.64740.42100.37640.058*
C130.56263 (8)0.56282 (13)0.38097 (10)0.0337 (3)
C140.47905 (8)0.58925 (13)0.38177 (10)0.0328 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0276 (6)0.0409 (7)0.0432 (7)0.0021 (5)0.0014 (5)0.0028 (5)
N20.0310 (6)0.0313 (6)0.0451 (7)0.0048 (5)0.0001 (5)0.0023 (5)
O10.0304 (5)0.0532 (6)0.0205 (4)0.0070 (4)0.0010 (3)0.0083 (4)
O20.0465 (6)0.0426 (6)0.0192 (4)0.0126 (4)0.0022 (4)0.0037 (4)
O30.0317 (5)0.0494 (6)0.0247 (5)0.0147 (4)0.0020 (4)0.0104 (4)
O40.0354 (5)0.0339 (5)0.0202 (4)0.0089 (4)0.0015 (3)0.0032 (4)
C10.0261 (6)0.0289 (6)0.0180 (6)0.0024 (5)0.0001 (4)0.0003 (5)
C20.0262 (6)0.0264 (6)0.0179 (6)0.0008 (5)0.0001 (4)0.0005 (4)
C30.0257 (6)0.0299 (6)0.0219 (6)0.0037 (5)0.0027 (4)0.0003 (5)
C40.0223 (6)0.0304 (6)0.0227 (6)0.0013 (5)0.0013 (4)0.0048 (5)
C50.0291 (6)0.0304 (6)0.0159 (5)0.0007 (5)0.0013 (4)0.0017 (5)
C60.0259 (6)0.0235 (6)0.0213 (6)0.0001 (4)0.0023 (4)0.0013 (4)
C70.0300 (6)0.0272 (6)0.0195 (6)0.0051 (5)0.0020 (4)0.0012 (5)
C80.0395 (7)0.0325 (7)0.0393 (8)0.0018 (6)0.0001 (6)0.0017 (6)
C90.0347 (7)0.0406 (9)0.0590 (11)0.0034 (6)0.0014 (7)0.0045 (7)
C100.0541 (10)0.0349 (8)0.0694 (12)0.0073 (7)0.0026 (8)0.0062 (8)
C110.0639 (11)0.0318 (8)0.0718 (13)0.0105 (7)0.0034 (9)0.0059 (8)
C120.0419 (8)0.0432 (9)0.0590 (11)0.0146 (7)0.0010 (7)0.0049 (8)
C130.0313 (7)0.0352 (8)0.0346 (7)0.0026 (5)0.0014 (5)0.0033 (6)
C140.0318 (7)0.0315 (7)0.0351 (7)0.0043 (5)0.0014 (5)0.0026 (5)
Geometric parameters (Å, º) top
N1—C81.3160 (19)C4—C51.3867 (17)
N1—C131.3862 (19)C5—C61.3937 (17)
N1—H10.8600C5—H50.9300
N2—C81.3200 (18)C6—C71.3888 (17)
N2—C141.3875 (19)C7—H70.9300
N2—H20.8600C8—H80.9300
O1—C11.2690 (15)C9—C101.372 (2)
O2—C11.2445 (15)C9—C141.382 (2)
O3—C41.3607 (14)C9—H90.9300
O3—H3A0.9261C10—C111.388 (3)
O4—C61.3573 (14)C10—H100.9300
O4—H4A0.9084C11—C121.364 (3)
C1—C21.5079 (17)C11—H110.9300
C2—C71.3879 (17)C12—C131.393 (2)
C2—C31.3899 (16)C12—H120.9300
C3—C41.3877 (17)C13—C141.3905 (19)
C3—H30.9300
C8—N1—C13108.82 (12)C7—C6—C5119.87 (11)
C8—N1—H1125.6C2—C7—C6119.88 (11)
C13—N1—H1125.6C2—C7—H7120.1
C8—N2—C14108.91 (12)C6—C7—H7120.1
C8—N2—H2125.5N1—C8—N2110.06 (13)
C14—N2—H2125.5N1—C8—H8125.0
C4—O3—H3A112.8N2—C8—H8125.0
C6—O4—H4A110.1C10—C9—C14116.38 (14)
O2—C1—O1124.35 (12)C10—C9—H9121.8
O2—C1—C2117.66 (11)C14—C9—H9121.8
O1—C1—C2117.97 (10)C9—C10—C11122.10 (16)
C7—C2—C3120.56 (11)C9—C10—H10119.0
C7—C2—C1118.74 (10)C11—C10—H10119.0
C3—C2—C1120.69 (10)C12—C11—C10122.07 (16)
C4—C3—C2119.19 (11)C12—C11—H11119.0
C4—C3—H3120.4C10—C11—H11119.0
C2—C3—H3120.4C11—C12—C13116.40 (15)
O3—C4—C5121.55 (11)C11—C12—H12121.8
O3—C4—C3117.70 (11)C13—C12—H12121.8
C5—C4—C3120.74 (11)N1—C13—C14106.32 (12)
C4—C5—C6119.69 (11)N1—C13—C12132.27 (14)
C4—C5—H5120.2C14—C13—C12121.41 (14)
C6—C5—H5120.2C9—C14—N2132.47 (13)
O4—C6—C7118.06 (11)C9—C14—C13121.63 (13)
O4—C6—C5122.07 (11)N2—C14—C13105.89 (12)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.861.872.7128 (18)168
N2—H2···O3i0.862.082.8510 (18)149
O3—H3A···O1ii0.931.722.6499 (16)179
O4—H4A···O2iii0.911.722.6289 (15)178
C8—H8···O2iv0.932.343.235 (2)162
Symmetry codes: (i) x+1, y, z+1/2; (ii) x+3/2, y+3/2, z1/2; (iii) x, y+1, z1/2; (iv) x+3/2, y+1/2, z.

Experimental details

Crystal data
Chemical formulaC7H7N2+·C7H5O4
Mr272.26
Crystal system, space groupOrthorhombic, Pbcn
Temperature (K)295
a, b, c (Å)16.297 (4), 10.600 (3), 14.649 (5)
V3)2530.6 (13)
Z8
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.40 × 0.38 × 0.36
Data collection
DiffractometerRigaku R-AXIS RAPID
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
23272, 2901, 2435
Rint0.037
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.041, 0.115, 1.09
No. of reflections2901
No. of parameters182
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.35, 0.29

Computer programs: PROCESS-AUTO (Rigaku, 1998), PROCESS-AUTO, CrystalStructure (Rigaku/MSC, 2002), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Selected bond lengths (Å) top
N1—C81.3160 (19)O1—C11.2690 (15)
N1—C131.3862 (19)O2—C11.2445 (15)
N2—C81.3200 (18)O3—C41.3607 (14)
N2—C141.3875 (19)O4—C61.3573 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.861.872.7128 (18)168
N2—H2···O3i0.862.082.8510 (18)149
O3—H3A···O1ii0.931.722.6499 (16)179
O4—H4A···O2iii0.911.722.6289 (15)178
C8—H8···O2iv0.932.343.235 (2)162
Symmetry codes: (i) x+1, y, z+1/2; (ii) x+3/2, y+3/2, z1/2; (iii) x, y+1, z1/2; (iv) x+3/2, y+1/2, z.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds