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Acta Crystallogr Sect E Struct Rep Online. 2009 June 1; 65(Pt 6): o1424.
Published online 2009 May 29. doi:  10.1107/S1600536809018510
PMCID: PMC2969548

(±)-3-Carb­oxy-2-(imidazol-3-ium-1-yl)­propanoate

Abstract

The title compound, C7H8N2O4, crystallizes as a zwitterion, with mol­ecules organized into mol­ecular sheets via carbox­yl–carboxyl­ate and N+—H(...)carboxyl­ate contacts. These sheets are constructed from translationally related mol­ecules that further link to neighboring motifs via π-stacking [centroid–centroid distance 3.504 (3) Å] and weak C—H(...)O contacts.

Related literature

For related compounds, see: Centnerzwer (1899 [triangle]); Pasteur (1853 [triangle]); Wheeler et al. (2008 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]).

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Object name is e-65-o1424-scheme1.jpg

Experimental

Crystal data

  • C7H8N2O4
  • M r = 184.15
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1424-efi5.jpg
  • a = 7.6328 (7) Å
  • b = 7.4701 (7) Å
  • c = 13.7616 (12) Å
  • β = 96.752 (1)°
  • V = 779.21 (12) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.13 mm−1
  • T = 296 K
  • 0.38 × 0.28 × 0.18 mm

Data collection

  • Bruker P4 CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2008 [triangle]) T min = 0.952, T max = 0.977
  • 4668 measured reflections
  • 1540 independent reflections
  • 1254 reflections with I > 2σ(I)
  • R int = 0.021

Refinement

  • R[F 2 > 2σ(F 2)] = 0.042
  • wR(F 2) = 0.115
  • S = 1.06
  • 1540 reflections
  • 126 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.24 e Å−3
  • Δρmin = −0.26 e Å−3

Data collection: APEX2 (Bruker, 2008 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT and XPREP (Bruker, 2008 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour, 2001 [triangle]); software used to prepare material for publication: X-SEED.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809018510/hk2685sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809018510/hk2685Isup2.hkl

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

Acknowledgments

Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund Type B, the National Science Foundation (grant No. 0722547) and Eastern Illinois University for support of this crystallographic investigation.

supplementary crystallographic information

Comment

Our recent reinvestigation of Pasteur's 1853 quasiracemates (Pasteur, 1853; Wheeler et al., 2008) has motivated us to explore other examples of these unusual materials of historical and supramolecular importance. In 1899, Centnerzwer reported that mixtures of (+)-chlorosuccinic acid and (-)-bromosuccinic acid formed a binary compound that also exhibited quasiracemic behavior (Centnerzwer, 1899). Our initial attempts to grow crystals of this quasiracemic phase were unsuccessful. This result was somewhat anticipated given that Centnerzwer's melting point phase diagrams showed the crystal stabilities of the homochiral phases more stable than the quasiracemate. We then turned our attention to investigating the effects of co-crystalline additives to crystal growth of this quasiracemate and the corresponding racemic and homochiral compounds. During the course of these co-crystal screening investigations, we observed the formation of crystals of the title compound from slow evaporation of a methanol:CH2Cl2 (1:1) solution of (±)-2-chlorosuccinic acid and imidazole.

The title compound, (I), formed from the substitution reaction of imidazole and 2-chlorosuccinic acid, crystallizes in space group P21/c as the imidazolium carboxylate zwitterion (Fig. 1). Inspection of the molecular structure reveals a resonance stabilized imidazolium ring with (N1—C7) - (N2—C7) = +0.038 Å. A search of the Cambridge Structural Database (CSD, Version 5.30 with August 2008 and February 2009 updates; Allen, 2002) for other N-alkylimidazolium fragments uncovered 44 organic structures. This collection shows similar bonding patterns to (I) with a concentration of Δ(N—C) values near 0.00, +0.01, and +0.03 Å.

The crystal structure of (I) is organized by a complex blend of strong and weak intermolecular contacts (Table 1). Neighboring molecules are linked by carboxyl···carboxylate interactions to give a catemeric motif that propagates along the a-axis (Fig. 2). This motif is extended by N2+H···carboxylate contacts to produce a molecular sheet in the ab plane. The participation of the imidazolium N+—H group in hydrogen bonding is also a common feature in the 44 structures retrieved from the CSD. Each of these structures show N+—H···A contacts with a diverse set of acceptors [A = oxygen(52), nitrogen(3), halogen(15), or π(2); 72 contacts]. Interestingly, each molecular sheet in (I) consists of translationally related molecules with imidazolium groups exposed on one side of the motif and carboxyl O4 atoms on the other side. The crystal structure of (I) is characterized by the stacking of these molecular sheets with adjacent motifs related by inversion symmetry and linked by either interdigitated imadazolium···imidazolium stacks [3.504 (3) Å] or weak C5—H5···O4 interactions (Fig. 3).

Experimental

Single crystals of the title compound were prepared by slow evaporation at room temperature of a methanol:CH2Cl2 (1:1) solution of (±)-2-chlorosuccinic acid and imidazole (1:1).

Refinement

H atoms (for OH and NH) were located in difference Fourier synthesis and refined isotropically. The remaining H atoms were positioned geometrically with C—H = 0.93, 0.98 and 0.97 Å, for aromatic, methine and metnylene H atoms, respectively, and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).

Figures

Fig. 1.
The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
Fig. 2.
A partial packing diagram of the title compound, showing molecular sheets constructed from carboxyl···carboxylate and N—H···O contacts [symmetry codes: (i) 1 + x, y, z, (ii) x, 1 + y, z; (iii) x ...
Fig. 3.
Projection showing alignment of molecular sheets with imidazolium π stacking and C—H···O interactions [symmetry codes: i) x, y - 1, z, (ii) x, 3/2 - y, 1/2 + z; (iii) x - 3, 3/2 - y, z - 1/2].
Fig. 4.
The tautomeric forms of the title compound.

Crystal data

C7H8N2O4F(000) = 384
Mr = 184.15Dx = 1.570 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1902 reflections
a = 7.6328 (7) Åθ = 6.0–54.6°
b = 7.4701 (7) ŵ = 0.13 mm1
c = 13.7616 (12) ÅT = 296 K
β = 96.752 (1)°Transparent prism, colourless
V = 779.21 (12) Å30.38 × 0.28 × 0.18 mm
Z = 4

Data collection

Bruker P4 CCD diffractometer1540 independent reflections
Radiation source: fine-focus sealed tube1254 reflections with I > 2σ(I)
graphiteRint = 0.021
[var phi] and ω scansθmax = 26.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2008)h = −9→9
Tmin = 0.952, Tmax = 0.977k = −9→8
4668 measured reflectionsl = −16→16

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)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.115H atoms treated by a mixture of independent and constrained refinement
S = 1.06w = 1/[σ2(Fo2) + (0.0548P)2 + 0.3288P] where P = (Fo2 + 2Fc2)/3
1540 reflections(Δ/σ)max < 0.001
126 parametersΔρmax = 0.24 e Å3
0 restraintsΔρmin = −0.26 e Å3

Special details

Experimental. The instrument used for data collection was a Bruker P4 with a APEXII CCD detector upgrade.
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)

xyzUiso*/Ueq
O11.00100 (17)1.13604 (17)0.63749 (11)0.0446 (4)
O21.09600 (17)0.86066 (19)0.61600 (13)0.0558 (5)
O30.42339 (18)0.9309 (2)0.62306 (10)0.0475 (4)
O40.4539 (2)0.8529 (3)0.77836 (13)0.0813 (7)
N10.77182 (17)0.72061 (19)0.57875 (10)0.0293 (3)
N20.8241 (2)0.4386 (2)0.57164 (14)0.0448 (4)
C10.9788 (2)0.9740 (2)0.62128 (12)0.0296 (4)
C20.7853 (2)0.9081 (2)0.61136 (12)0.0290 (4)
H20.71630.98190.56190.035*
C30.7111 (2)0.9343 (3)0.70828 (13)0.0367 (4)
H3A0.77380.85510.75630.044*
H3B0.73551.05610.73010.044*
C40.5163 (2)0.9005 (3)0.70683 (14)0.0378 (4)
C50.7043 (2)0.6631 (3)0.48706 (14)0.0391 (5)
H50.64660.73300.43730.047*
C60.7375 (3)0.4871 (3)0.48305 (16)0.0474 (5)
H60.70710.41210.42980.057*
C70.8438 (2)0.5806 (2)0.62777 (15)0.0400 (5)
H70.89930.58300.69170.048*
H10.301 (5)0.920 (4)0.630 (2)0.098 (10)*
H30.870 (3)0.333 (4)0.5910 (17)0.061 (7)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0352 (7)0.0277 (7)0.0694 (10)−0.0049 (5)−0.0004 (6)−0.0018 (6)
O20.0231 (7)0.0362 (8)0.1069 (13)0.0015 (6)0.0032 (7)−0.0128 (8)
O30.0277 (7)0.0630 (10)0.0517 (9)−0.0032 (6)0.0042 (6)0.0051 (7)
O40.0476 (10)0.1370 (19)0.0607 (11)−0.0101 (11)0.0125 (8)0.0310 (11)
N10.0244 (7)0.0263 (8)0.0370 (8)−0.0015 (5)0.0021 (6)−0.0016 (6)
N20.0378 (9)0.0255 (9)0.0715 (12)0.0012 (7)0.0078 (8)0.0026 (8)
C10.0255 (8)0.0299 (9)0.0330 (9)−0.0015 (7)0.0021 (6)−0.0006 (7)
C20.0249 (8)0.0259 (9)0.0356 (9)0.0001 (6)0.0006 (6)−0.0008 (7)
C30.0290 (9)0.0422 (11)0.0387 (10)0.0019 (8)0.0028 (7)−0.0039 (8)
C40.0308 (9)0.0384 (10)0.0449 (11)0.0021 (7)0.0078 (8)0.0001 (8)
C50.0409 (10)0.0372 (11)0.0383 (10)−0.0025 (8)0.0007 (8)−0.0041 (8)
C60.0541 (13)0.0360 (11)0.0527 (13)−0.0051 (9)0.0079 (10)−0.0120 (9)
C70.0374 (10)0.0317 (10)0.0492 (11)−0.0007 (8)−0.0023 (8)0.0039 (8)

Geometric parameters (Å, °)

O1—C11.239 (2)C1—C21.548 (2)
O2—C11.240 (2)C2—C31.522 (2)
O3—C41.300 (2)C2—H20.9800
O3—H10.95 (3)C3—C41.506 (3)
O4—C41.197 (2)C3—H3A0.9700
N1—C71.328 (2)C3—H3B0.9700
N1—C51.374 (2)C5—C61.341 (3)
N1—C21.471 (2)C5—H50.9300
N2—C71.310 (3)C6—H60.9300
N2—C61.366 (3)C7—H70.9300
N2—H30.89 (3)
C4—O3—H1110 (2)C4—C3—H3A108.3
C7—N1—C5107.96 (15)C2—C3—H3A108.3
C7—N1—C2125.82 (15)C4—C3—H3B108.3
C5—N1—C2125.65 (15)C2—C3—H3B108.3
C7—N2—C6108.73 (17)H3A—C3—H3B107.4
C7—N2—H3121.9 (16)O4—C4—O3123.55 (18)
C6—N2—H3129.2 (16)O4—C4—C3121.78 (18)
O1—C1—O2126.38 (16)O3—C4—C3114.66 (16)
O1—C1—C2115.82 (15)C6—C5—N1106.96 (18)
O2—C1—C2117.74 (15)C6—C5—H5126.5
N1—C2—C3111.71 (14)N1—C5—H5126.5
N1—C2—C1111.19 (13)C5—C6—N2107.30 (18)
C3—C2—C1109.36 (13)C5—C6—H6126.3
N1—C2—H2108.2N2—C6—H6126.3
C3—C2—H2108.2N2—C7—N1109.04 (17)
C1—C2—H2108.2N2—C7—H7125.5
C4—C3—C2115.82 (15)N1—C7—H7125.5
C7—N1—C2—C3−59.2 (2)C2—C3—C4—O4152.5 (2)
C5—N1—C2—C3130.59 (17)C2—C3—C4—O3−28.9 (2)
C7—N1—C2—C163.3 (2)C7—N1—C5—C60.1 (2)
C5—N1—C2—C1−106.93 (18)C2—N1—C5—C6171.80 (16)
O1—C1—C2—N1172.03 (15)N1—C5—C6—N20.1 (2)
O2—C1—C2—N1−10.5 (2)C7—N2—C6—C5−0.3 (2)
O1—C1—C2—C3−64.1 (2)C6—N2—C7—N10.3 (2)
O2—C1—C2—C3113.28 (18)C5—N1—C7—N2−0.3 (2)
N1—C2—C3—C4−64.66 (19)C2—N1—C7—N2−171.95 (16)
C1—C2—C3—C4171.82 (15)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O3—H1···O2i0.95 (3)1.62 (3)2.5440 (18)163 (3)
N2—H3···O1ii0.89 (3)1.85 (3)2.732 (2)170 (2)
C7—H7···O1iii0.932.423.333 (2)168
C5—H5···O4iv0.932.573.260 (3)131

Symmetry codes: (i) x−1, y, z; (ii) x, y−1, z; (iii) −x+2, y−1/2, −z+3/2; (iv) x, −y+3/2, z−1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2685).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Barbour, L. J. (2001). J. Supramol. Chem.1, 189–191.
  • Bruker (2008). APEX2, SADABS, SAINT and XPREP Bruker AXS Inc., Madison, Wisconsin, USA.
  • Centnerzwer, M. Z. (1899). Z. Phys. Chem.29, 715–725.
  • Pasteur, L. (1853). Ann. Chim. Phys.38, 437–483.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Wheeler, K. A., Grove, R. C., Davis, R. E. & Kassel, W. S. (2008). Angew. Chem. Int. Ed.47, 78–81. [PubMed]

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