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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2632.
Published online 2009 October 3. doi:  10.1107/S160053680903952X
PMCID: PMC2971242

Bis(2-methyl­imidazolium) fumarate dihydrate

Abstract

In the title compound, 2C4H7N2 +·C4H2O4 2−·2H2O, the asymmetric unit consists of one 2-methyl­imidazolium cation, half a fumarate dianion and one water mol­ecule. There is an inversion center at the mid-point of the central C—C bond of the fumarate anion. In the crystal structure, mol­ecules are linked into a three-dimensional network by inter­molecular N—H(...)O, O—H(...)O and weak C—H(...)O hydrogen bonds. In addition, there are weak π–π stacking inter­actions with centroid–centroid distances of 3.640 (1) Å.

Related literature

For background information on cocrystals, see: Aakeröy & Salmon (2005 [triangle]); Aakeröy et al. (2007 [triangle]); Childs & Hardcastle (2007 [triangle]); Childs et al. (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o2632-scheme1.jpg

Experimental

Crystal data

  • 2C4H7N2 +·C4H2O4 2−·2H2O
  • M r = 316.32
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2632-efi1.jpg
  • a = 8.3912 (8) Å
  • b = 7.3195 (7) Å
  • c = 14.2475 (13) Å
  • β = 106.624 (2)°
  • V = 838.50 (14) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 294 K
  • 0.20 × 0.10 × 0.04 mm

Data collection

  • Bruker SMART APEX CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2001 [triangle]) T min = 0.970, T max = 0.996
  • 9171 measured reflections
  • 1920 independent reflections
  • 1261 reflections with I > 2σ(I)
  • R int = 0.036

Refinement

  • R[F 2 > 2σ(F 2)] = 0.051
  • wR(F 2) = 0.152
  • S = 1.06
  • 1920 reflections
  • 114 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.25 e Å−3
  • Δρmin = −0.18 e Å−3

Data collection: SMART (Bruker, 2001 [triangle]); cell refinement: SAINT-Plus (Bruker, 2001 [triangle]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: PLATON.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680903952X/lh2915sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680903952X/lh2915Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The author thanks Xiangfan University for financial support.

supplementary crystallographic information

Comment

Studies on cocrystals or organic salts have been expanded rapidly in recent years owing to their potential application in active pharmaceutical ingredients (Aakeröy et al., 2007; Childs et al., 2007; Hilds & Hardcastle, 2007). Herein, the crystal structure an organic salt formed by the reaction of 2-methylimidazole and fumaric acid is reported.

In the title compound (I), the asymmetric unit is composed of one 2-methylimidazolium cation, half a fumarate dianion and one water molecule. There is an inversion center at the midpoint of the C2-C2(1-x, -y, 1-z) bond. The title complex can be regarded as an organic salt according to Aakeröy & Salmon (2005). The fumaric acid molecule is deprotonated, with both the protons transferred to the imidazole N atom leading to each a fumarate dianion and an imidazolium cation (Fig.1), which can be evidenced to some extent by the delocaliztion of the carboxyl C-O bonds (C1-O1 1.249 (2)Å, C1-O2 1.253 (2)Å) and the imidazolium C-N bonds (C3-N1 1.325 (2)Å, C3-N2 1.332 (2)Å).

In the crystal packing, by a combination of two N-H···O, two O-H···O and one C-H···O hydrogen bonds (Table 1) and one π-π interaction [Cg···Cg(1-x, 1-y, -z) = 3.640 (1)Å, Cg is the centroid defined by atoms C3-C5/N1/N2], molecules in (I) are linked into a three-dimensional network (Fig.2).

Experimental

All the reagents and solvents were used as obtained without further purification. A 1:2 molar amounts of fumaric acid (0.2 mmol, 23.2 mg) and 2-methyl-imidazole (0.4 mmol, 32.8 mg) were dissolved in 95% methanol (10 ml). The resulting solution was kept in air for one week. Plate crystals of (I) suitable for single-crystal X-ray diffraction analysis were grown by slow evaporation of the solution at the bottom of the vessel.

Refinement

H atoms bonded to C atoms were located in difference maps and subsequently treated in a riding-model approximation, with C–H = 0.93 Å (aromatic), 0.96Å (methyl), Uiso(H) = 1.2Ueq( aromatic C) and 1.5Ueq(methyl C). H atoms bonded to N and O atoms were also found in difference maps and their distances were refined freely (see Table 1 for the distances), and the Uiso(H) values being set k times of their carrier atoms ( k = 1.2 for N1 and 1.5 for O atoms and N2)

Figures

Fig. 1.
Molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H-bonds are shown in dashed lines. (Symmetry code (iv): 1-x, -y, 1-z).
Fig. 2.
Part of the crystal structure of (I), showing the formation of the three-dimensional network by N-H···O, O-H···O and C-H···O hydrogen-bonds and π–π stacking ...

Crystal data

2C4H7N2+·C4H2O42·2H2OF(000) = 336
Mr = 316.32Dx = 1.253 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 430 reflections
a = 8.3912 (8) Åθ = 3.0–22.0°
b = 7.3195 (7) ŵ = 0.10 mm1
c = 14.2475 (13) ÅT = 294 K
β = 106.624 (2)°Plate, colorless
V = 838.50 (14) Å30.20 × 0.10 × 0.04 mm
Z = 4

Data collection

Bruker SMART APEX CCD area-detector diffractometer1920 independent reflections
Radiation source: fine focus sealed Siemens Mo tube1261 reflections with I > 2σ(I)
graphiteRint = 0.036
0.3° wide ω exposures scansθmax = 27.5°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2001)h = −10→10
Tmin = 0.970, Tmax = 0.996k = −9→9
9171 measured reflectionsl = −18→18

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.051Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.152H atoms treated by a mixture of independent and constrained refinement
S = 1.06w = 1/[σ2(Fo2) + (0.071P)2 + 0.1419P] where P = (Fo2 + 2Fc2)/3
1920 reflections(Δ/σ)max = 0.027
114 parametersΔρmax = 0.25 e Å3
0 restraintsΔρmin = −0.18 e Å3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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)

xyzUiso*/Ueq
C10.5386 (2)0.0238 (2)0.37212 (12)0.0401 (4)
C20.5606 (2)0.0086 (2)0.48028 (11)0.0428 (5)
H20.66850.01170.52200.051*
C30.6978 (3)0.1228 (2)0.10113 (13)0.0471 (5)
C40.4614 (3)0.2353 (3)0.11177 (14)0.0539 (5)
H40.37500.26820.13720.065*
C50.4689 (3)0.2673 (3)0.02039 (14)0.0516 (5)
H50.38950.3266−0.02940.062*
C60.8635 (3)0.0358 (3)0.12642 (17)0.0702 (7)
H6A0.94320.11420.16980.105*
H6B0.89580.01590.06780.105*
H6C0.8593−0.07910.15810.105*
N10.6039 (2)0.1456 (2)0.16080 (11)0.0517 (5)
H1A0.633 (2)0.101 (3)0.2268 (16)0.062*
N20.6165 (2)0.1953 (2)0.01497 (11)0.0482 (5)
H2A0.654 (3)0.191 (3)−0.0380 (18)0.074 (7)*
O10.66885 (18)0.0373 (2)0.34674 (9)0.0569 (4)
O20.39407 (17)0.0221 (2)0.31492 (8)0.0556 (4)
O30.2028 (3)0.3054 (3)0.34768 (13)0.1009 (8)
H3B0.172 (5)0.371 (6)0.301 (3)0.151*
H3A0.256 (5)0.221 (5)0.335 (3)0.151*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0536 (12)0.0402 (9)0.0280 (8)0.0051 (8)0.0144 (8)0.0001 (7)
C20.0490 (12)0.0515 (11)0.0276 (9)0.0012 (9)0.0102 (7)0.0001 (7)
C30.0631 (13)0.0426 (10)0.0375 (9)−0.0092 (9)0.0172 (9)−0.0010 (8)
C40.0635 (14)0.0604 (13)0.0422 (10)−0.0028 (11)0.0224 (10)0.0006 (9)
C50.0624 (14)0.0513 (11)0.0402 (10)−0.0050 (10)0.0132 (9)0.0023 (8)
C60.0735 (17)0.0671 (15)0.0718 (15)0.0029 (12)0.0235 (13)0.0024 (12)
N10.0688 (12)0.0565 (10)0.0318 (8)−0.0064 (9)0.0178 (8)0.0032 (7)
N20.0685 (12)0.0476 (9)0.0327 (8)−0.0111 (8)0.0210 (8)−0.0010 (7)
O10.0581 (9)0.0826 (11)0.0349 (7)0.0046 (7)0.0214 (6)0.0103 (6)
O20.0570 (9)0.0780 (10)0.0302 (6)0.0073 (7)0.0100 (6)−0.0072 (6)
O30.150 (2)0.1188 (17)0.0515 (9)0.0793 (14)0.0575 (12)0.0364 (10)

Geometric parameters (Å, °)

C1—O11.249 (2)C4—H40.9300
C1—O21.253 (2)C5—N21.368 (3)
C1—C21.503 (2)C5—H50.9300
C2—C2i1.301 (3)C6—H6A0.9600
C2—H20.9300C6—H6B0.9600
C3—N11.325 (2)C6—H6C0.9600
C3—N21.332 (2)N1—H1A0.96 (2)
C3—C61.477 (3)N2—H2A0.90 (2)
C4—C51.342 (3)O3—H3B0.80 (4)
C4—N11.368 (3)O3—H3A0.81 (4)
O1—C1—O2125.22 (15)N2—C5—H5126.8
O1—C1—C2116.20 (16)C3—C6—H6A109.5
O2—C1—C2118.57 (17)C3—C6—H6B109.5
C2i—C2—C1124.6 (2)H6A—C6—H6B109.5
C2i—C2—H2117.7C3—C6—H6C109.5
C1—C2—H2117.7H6A—C6—H6C109.5
N1—C3—N2107.42 (19)H6B—C6—H6C109.5
N1—C3—C6126.08 (18)C3—N1—C4109.04 (16)
N2—C3—C6126.5 (2)C3—N1—H1A123.6 (13)
C5—C4—N1107.61 (19)C4—N1—H1A127.4 (13)
C5—C4—H4126.2C3—N2—C5109.55 (17)
N1—C4—H4126.2C3—N2—H2A123.4 (15)
C4—C5—N2106.38 (19)C5—N2—H2A127.0 (15)
C4—C5—H5126.8H3B—O3—H3A110 (3)
O1—C1—C2—C2i−179.1 (2)C5—C4—N1—C30.1 (2)
O2—C1—C2—C2i0.9 (3)N1—C3—N2—C50.7 (2)
N1—C4—C5—N20.3 (2)C6—C3—N2—C5−178.31 (19)
N2—C3—N1—C4−0.5 (2)C4—C5—N2—C3−0.6 (2)
C6—C3—N1—C4178.5 (2)

Symmetry codes: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N2—H2A···O3ii0.90 (2)1.79 (2)2.682 (2)172 (2)
O3—H3B···O2iii0.80 (4)1.94 (4)2.733 (2)177 (4)
C5—H5···O1iv0.932.383.308 (3)175
N1—H1A···O10.96 (2)1.71 (2)2.668 (2)173 (2)
O3—H3A···O20.81 (4)1.94 (4)2.742 (2)176 (4)

Symmetry codes: (ii) x+1/2, −y+1/2, z−1/2; (iii) −x+1/2, y+1/2, −z+1/2; (iv) x−1/2, −y+1/2, z−1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH2915).

References

  • Aakeröy, C. B., Fasulo, M. E. & Desper, J. (2007). Mol. Pharm.4, 317–322. [PubMed]
  • Aakeröy, C. B. & Salmon, D. J. (2005). CrystEngComm, 7, 439–448.
  • Bruker (2001). SAINT-Plus, SMART and SADABS Bruker AXS, Inc., Madison, Wisconsin, USA.
  • Childs, S. L. & Hardcastle, K. I. (2007). Cryst. Growth Des.7, 1291–1304.
  • Childs, S. L., Stahly, G. P. & Park, A. (2007). Mol. Pharm.4, 323–338. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography