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The asymmetric unit of the title compound, C10H10N22+·2C2HO4-, consists of one half of a 4,4'-bipyridinium cation, which has inversion symmetry, and a hydrogen oxalate anion, in which an intra­molecular hydrogen bond exists. The cations and anions are connected by O-H...O, N-H...O and C-H...O hydrogen bonds, forming a two-dimensional network, whereas [pi]-[pi] stacking inter­actions involving the 4,4'-bipyridinium cations lead to the formation of a three-dimensional supra­molecular structure. An unusual deca-atomic ring is formed between two hydrogen oxalate anions, which are linked side-to-side via O-H...O hydrogen-bonding inter­actions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270111028162/su3065sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270111028162/su3065Isup2.hkl
Contains datablock I

cml

Chemical Markup Language (CML) file https://doi.org/10.1107/S0108270111028162/su3065Isup3.cml
Supplementary material

CCDC reference: 846634

Comment top

In crystal engineering, the construction of functional materials with desired properties from molecules or ions is achieved by the use of appropriate building blocks. These constituents can provide a large number of conformations in the crystal; therefore, it is very difficult to predict the final structure. However, the most widely used structural organizing forces in crystal engineering have been hydrogen bonds, owing to such properties of theirs as directionality, selectivity and strength, allowing the preparation of finally predictable structural aggregates which may have different characteristics. It is well known that the utilization of ions which can make hydrogen bonds allows the simultaneous exploitation of the directionality and reproducibility of these interactions and the strength of the Coulomb field generated by the ionic charges (Braga et al., 2002). In general, noncovalent, intermolecular interactions such as hydrogen bonds and ππ stacking are widely used in molecular aggregation because they can adjust the dimensionality (one-, two- and three-dimensional supramolecular networks) and lead to new topologies and desired functions of supramolecular assemblies.

The ligand 4,4'-bipyridine is an excellent synthon owing to its rigidity and ability to act as a metal-binding ligand or hydrogen-bonding acceptor, and, when protonated, the resulting cation can serve as a hydrogen-bonding donor. In addition, it can also induce ππ stacking interactions. So far, many supramolecular architectures involving 4,4'-bipyridine as a versatile molecular building block have been reported (Jayaraman et al., 2006; Ruiz-Pérez et al., 2004; Iyere et al., 2003). In metal–organic frameworks, especially in the class of porous polymeric materials, metal ions are often linked by this organic bridging ligand (James, 2003). Oxalic acid and its anions can act as both donors and acceptors for hydrogen bonds. It is interesting to note that, because of the extraordinary coordination and electronic properties of the oxalate anion, a huge number of homo- and heteropolynuclear oxalate-based complexes of different nuclearity and dimensionality have been prepared (Jurić et al., 2006).

Related to our current magneto-structural studies on oxalate-based mono- and polynuclear transition metal complexes, we have recently extended our investigations to the reactions of oxalate salts with N-donor ligands, with the aim of preparing new organic frameworks. Our interest has been to determine the influence of particular components of such systems on the structural and functional characteristics of new supramolecular assemblies. We report herein on the supramolecular crystal structure of 4,4'-bipyridinium bis(hydrogen oxalate), (I), which contains hydrogen bonds and ππ stacking interactions. Further research on other similar oxalate systems is in progress.

The molecular structure of (I) (Fig. 1) consists of a diprotonated 4,4'-bipyridine cation and two hydrogen oxalate anions which are linked together by noncovalent interactions giving a three-dimensional architecture. There is a crystallographic inversion centre in the middle of the cation, so that the asymmetric unit contains a half of the cation and one anion. In the cation, as in other 4,4'-bipyridinium salts (Ma et al., 2005; Muthiah et al., 2003; Wang & Wei, 2006), there is an increase of the internal angle [C3—N1—C7 = 121.63 (14)°] compared with the corresponding angle in the neutral 4,4'-bipyridine molecule [115.45 (19)°; Boag et al., 1999]. This increase in angle confirms the protonation of the N atoms in 4,4'-bipyridine. The pyridyl ring of the cation is planar [maximum deviation from the mean plane = 0.004 (2) Å]. The hydrogen oxalate anion is almost planar, with O1—C1—C2—O4 and O2—C1—C2—O3 torsion angles of 0.7 (2) and 1.1 (2)°, respectively.

According to Steiner (2002), D—H···A interactions with distances of up to 3.0 or even 3.2 Å should be considered as potential hydrogen bonding. Also, an angular cutoff can be set at >90° or, somewhat more conservatively, at >110°. Based on these settings, an intramolecular O—H···H hydrogen bond exists in the hydrogen oxalate anion [Table 1 and Fig. 2 (grey dashed lines)], with graph-set descriptor S(5) (Etter et al., 1990). Further, the cations and anions are interconnected by means of three D—H···A hydrogen bonds forming an infinite one-dimensional motif parallel to the [121] direction (Fig. 2 and Table 1). Taking into consideration the classification of hydrogen bonds by Jeffrey (Steiner, 2002), H1N from the protonated pyridyl ring of the cation is involved in one moderate and one weak hydrogen bond with O atoms of the hydrogen oxalate anion from the neighbouring symmetry unit [the H1N···O2ii and H1N ···O3ii distances are 2.423 (18) and 1.62 (2) Å, respectively; symmetry code: (ii) -x+2, -y+1, -z+1], making the ring motif R12(5) (Fig. 2). With regard to the intramolecular hydrogen bond, an R22(4) ring motif linking two inversion-related hydrogen oxalate anions can be recognized in Fig. 2. However, a second-order hydrogen-bonded ring motif, R22(10), is more obvious; this unusual deca-atomic ring is formed between two hydrogen oxalate anions linked side-to-side via -O—H···O- hydrogen-bonding interactions (Table 1 and Fig. 2; Braga et al., 2002). An intramolecular O—H···O hydrogen bond may be the cause of the sharp hydrogen-bond angle between two hydrogen oxalate anions [O1—H1···O4i = 142.5 (16)°; symmetry code: (i) -x+1, -y, -z; Table 2]. In addition, it is well known that in cyclic hydrogen-bonded dimers fairly short H···H contacts occur and destabilize such arrays, forcing angles to be very bent (Steiner, 2002).

All of these ring hydrogen-bonding motifs are further linked into a chain by hydrogen-bonding motifs with the graph-set descriptors C33(17), C33(18) or C33(19), depending on the choice of the different paths chosen through the hydrogen bonds. The infinite one-dimensional chains are connected via C···H—O bonds generating a two-dimensional network (Fig. 2 and Table 1).

Stacking interactions of the aromatic systems play an equally important role in the structure of (I), linking the two-dimensional hydrogen-bonding pattern to form a three-dimensional supramolecular architecture. The 4,4'-bipyridinium cations related by the inversion centres are grouped through ππ interactions parallel to the a axis (Fig. 3), each cation belonging to a different hydrogen-bonding layer. The centroid–centroid distance of two pyridyl rings related by an inversion centre is 4.3865 (10) Å, but the distance between the centres of the two stacking pyridyl rings is equal to the a axis, i.e. 3.6954 (2) Å, whereas the perpendicular distance between their mean planes is 3.3373 (6) Å. The above structural analysis, taking into account the ππ interactions in compound (I), is consistent with the view that the aromatic groups stack when the parallel molecular planes are separated approximately by the interplanar distances of ca 3.3–3.8 Å (Janiak, 2000). A pyridine-fragment search made by Janiak has revealed that centroid–centroid contacts between two pyridine fragments start slightly below 3.4 Å (strong interactions are around 3.3 Å and weaker interactions lie above 3.6 Å) and a relative maximum in a number of examples was found around 3.8 Å.

A search of the Cambridge Structural Database (CSD, Version 3.2, update of May 2011; Allen, 2002) revealed that there are a large number of structures containing the 4,4'-bipyridinium cation or an hydrogen oxalate anion, with different simple or complex organic (metal–organic) anions or cations, respectively. Only one structure containing both the 4,4'-bipyridinium cation and an hydrogen oxalate anion was found in the CSD, but the structure also incorporates a complex anion with bivalent Fe (Yang et al., 2007). These three kinds of ions generate a supramolecular architecture which is different from that of (I). There are only three structures so far (Vaidhyanathan et al., 2001; Braga et al., 2002) in which hydrogen oxalate anions form a deca-atomic dimer joined together via the -O—H···O- interaction, as observed in compound (I). The intradimer O1···O4 distance [2.5941 (16) Å] in (I) is shorter than the corresponding distances in the structures mentioned above, where the O(H)···O distances are in the range 2.619–2.741 Å.

Related literature top

For related literature, see: Allen (2002); Androš et al. (2010); Boag et al. (1999); Braga et al. (2002); Etter et al. (1990); Iyere et al. (2003); James (2003); Janiak (2000); Jayaraman et al. (2006); Jurić et al. (2006); Ma et al. (2005); Muthiah et al. (2003); Nakamoto (2009); Ruiz-Pérez, Lorenzo-Luis, Hernández-Molina, Laz, Gili & Julve (2004); Steiner (2002); Vaidhyanathan et al. (2001); Wang & Wei (2006); Yang et al. (2007).

Experimental top

To an aqueous solution (5 ml) of 4,4'-bipyridine (40.8 mg, 0.2 mmol) an aqueous solution (2 ml) of 1 M HCl and an oxalatotantalate(V) solution (1 ml) [m(Ta) = 17.8 mg; 0.1 mmol (Androš et al., 2010)] were added dropwise by stirring at room temperature. A small amount of a white precipitate soon formed which was removed by filtration. Over a 2 d period, colourless plate-like crystals of (I) were obtained. They were separated and dried in air (yield 15%). Elemental analysis for C14H12N2O8 found: C 49.89, H 3.52, N 8.01%; calculated: C 50.01, H 3.59, N 8.23%.

Refinement top

C-bound H atoms were included in calculated positions and treated as riding [C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C)]. Difference Fourier maps for the structure of (I) (Fig. 4) indicate that the H atoms attached to N1 and O1 of the 4,4'-bipyridine and carboxylate group, respectively, could be located and were refined freely. These H atoms are involved in relatively strong or moderate hydrogen bonds, which could be the reason why the N1—H1N and O1—H1 distances are refined as relatively long. In support of this view, one can find in the review article of Steiner (2002) that the internuclear X—H bond length is fairly constant only in weak and moderate hydrogen bonds, whereas it is significantly elongated in strong ones. Additionally, the NH hydrogens of the pyridinium ring participate in two hydrogen bonds (N1—H1N···O2 and N1—H1N···O3; Table 1), and hence are more likely to be elongated.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2006); cell refinement: CrysAlis PRO (Oxford Diffraction, 2006); data reduction: CrysAlis PRO (Oxford Diffraction, 2006); program(s) used to solve structure: SIR92 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. A view of the molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii. The two halves of the 4,4'-bipyridinium cation are related by the symmetry operator (a) -x, -y, -z+1.
[Figure 2] Fig. 2. Hydrogen-bonding pattern with marked motifs parallel to the (121) plane in the crystal packing of (I). Black dashed lines represent intermolecular hydrogen bonds, whereas dotted lines represent C—H···O bonds. H atoms bound to C atoms which are not involved in C—H···O bonds have been omitted for clarity.
[Figure 3] Fig. 3. The crystal packing of the 4,4'-bipyridinium cations, linked by the ππ interactions of aromatic rings parallel to the a axis, and hydrogen oxalate anions.
[Figure 4] Fig. 4. Difference Fourier maps for the structure of (I), showing (a) the environment of the 4,4'-bipyridinium cation and (b) the environment of the hydrogen oxalate anion, indicate that the H atoms attached to the N1 and O1 atoms could be located and they were freely refined.
4,4'-bipyridineium bis(2-hydroxy-2-oxoacetate) top
Crystal data top
C10H10N22+·2C2HO4Z = 1
Mr = 336.26F(000) = 174
Triclinic, P1Dx = 1.687 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 3.6954 (2) ÅCell parameters from 1494 reflections
b = 9.8579 (7) Åθ = 3.9–29.1°
c = 10.4254 (8) ŵ = 0.14 mm1
α = 116.081 (7)°T = 150 K
β = 97.214 (5)°Plate, colourless
γ = 97.487 (5)°0.3 × 0.2 × 0.1 mm
V = 331.00 (4) Å3
Data collection top
Oxford Diffraction KM-4/Xcalibur
diffractometer with a Sapphire3 detector
1475 independent reflections
Radiation source: Enhance (Mo) X-ray Source1134 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.021
Detector resolution: 16.3426 pixels mm-1θmax = 29.1°, θmin = 3.9°
ω scansh = 34
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2006)
k = 1112
Tmin = 0.682, Tmax = 1.000l = 1314
2408 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.096All H-atom parameters refined
S = 0.99 w = 1/[σ2(Fo2) + (0.0679P)2]
where P = (Fo2 + 2Fc2)/3
1475 reflections(Δ/σ)max < 0.001
117 parametersΔρmax = 0.27 e Å3
0 restraintsΔρmin = 0.27 e Å3
Crystal data top
C10H10N22+·2C2HO4γ = 97.487 (5)°
Mr = 336.26V = 331.00 (4) Å3
Triclinic, P1Z = 1
a = 3.6954 (2) ÅMo Kα radiation
b = 9.8579 (7) ŵ = 0.14 mm1
c = 10.4254 (8) ÅT = 150 K
α = 116.081 (7)°0.3 × 0.2 × 0.1 mm
β = 97.214 (5)°
Data collection top
Oxford Diffraction KM-4/Xcalibur
diffractometer with a Sapphire3 detector
1475 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2006)
1134 reflections with I > 2σ(I)
Tmin = 0.682, Tmax = 1.000Rint = 0.021
2408 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0360 restraints
wR(F2) = 0.096All H-atom parameters refined
S = 0.99Δρmax = 0.27 e Å3
1475 reflectionsΔρmin = 0.27 e Å3
117 parameters
Special details top

Experimental. Specroscopic data for compound (I): IR(KBr, cm-1) : 3430 [ν(OH)], 1718 and 1631 [νas(CO)], 1486 and 1238 [νs(CO)] and 804 [δ(OCO)]. Other absorptions in the spectra correspond to different vibrations of the 4,4'-bipyridinum cation; the most important of them are located at 3125 [ν(CH)], 1947 [ν(NH+)], 1594 [ν(CC) + ν(CN)] and 608 [δ(CH)] (Nakamoto, 2009).

Absorption correction: Oxford Diffraction (2006). Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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
N10.5661 (3)0.36954 (13)0.65192 (12)0.0181 (3)
C30.4629 (4)0.28742 (15)0.50631 (14)0.0189 (4)
C40.2378 (4)0.14177 (15)0.44369 (14)0.0185 (4)
C50.1201 (4)0.07872 (14)0.53168 (14)0.0154 (4)
C60.2372 (4)0.16850 (15)0.68293 (15)0.0200 (4)
C70.4580 (4)0.31361 (16)0.74039 (15)0.0224 (4)
O10.8258 (3)0.12413 (11)0.07841 (10)0.0250 (3)
O21.1664 (3)0.36004 (11)0.04696 (11)0.0275 (3)
O30.9530 (3)0.38142 (11)0.29721 (10)0.0224 (3)
O40.6039 (3)0.14264 (11)0.16365 (10)0.0245 (3)
C10.9575 (4)0.25304 (16)0.04372 (15)0.0194 (4)
C20.8252 (4)0.25926 (15)0.18141 (14)0.0175 (4)
H1N0.754 (6)0.476 (2)0.693 (2)0.064 (7)*
H30.543130.328660.447360.0227*
H40.164460.085610.342710.0222*
H60.165460.129850.744830.0240*
H70.532610.373180.841020.0268*
H10.675 (5)0.051 (2)0.066 (2)0.048 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0190 (6)0.0159 (5)0.0177 (6)0.0008 (4)0.0040 (5)0.0071 (5)
C30.0220 (8)0.0195 (7)0.0172 (7)0.0040 (5)0.0060 (6)0.0098 (6)
C40.0219 (8)0.0182 (7)0.0123 (6)0.0017 (5)0.0025 (5)0.0053 (5)
C50.0138 (7)0.0170 (7)0.0156 (6)0.0045 (5)0.0045 (5)0.0070 (5)
C60.0233 (8)0.0198 (7)0.0151 (7)0.0013 (5)0.0049 (5)0.0079 (5)
C70.0269 (8)0.0217 (7)0.0146 (7)0.0012 (6)0.0039 (6)0.0068 (6)
O10.0338 (6)0.0194 (5)0.0146 (5)0.0068 (4)0.0072 (4)0.0043 (4)
O20.0355 (7)0.0226 (5)0.0195 (5)0.0063 (4)0.0075 (4)0.0084 (4)
O30.0279 (6)0.0185 (5)0.0148 (5)0.0034 (4)0.0051 (4)0.0044 (4)
O40.0300 (6)0.0208 (5)0.0167 (5)0.0052 (4)0.0066 (4)0.0059 (4)
C10.0214 (7)0.0190 (7)0.0149 (7)0.0003 (5)0.0033 (5)0.0064 (5)
C20.0190 (7)0.0188 (7)0.0141 (6)0.0015 (5)0.0033 (5)0.0078 (5)
Geometric parameters (Å, º) top
O1—C11.3166 (18)C4—C51.396 (2)
O2—C11.208 (2)C5—C5i1.492 (2)
O3—C21.2494 (17)C5—C61.3995 (19)
O4—C21.247 (2)C6—C71.375 (2)
O1—H10.92 (2)C3—H30.9300
N1—C71.340 (2)C4—H40.9300
N1—C31.3412 (17)C6—H60.9300
N1—H1N1.05 (2)C7—H70.9300
C3—C41.381 (2)C1—C21.552 (2)
C1—O1—H1113.0 (12)C3—C4—H4120.00
C3—N1—C7121.63 (14)C5—C4—H4120.00
C3—N1—H1N116.7 (10)C7—C6—H6120.00
C7—N1—H1N121.5 (10)C5—C6—H6120.00
N1—C3—C4120.17 (14)N1—C7—H7120.00
C3—C4—C5120.12 (12)C6—C7—H7120.00
C4—C5—C5i121.78 (12)O1—C1—C2116.09 (14)
C4—C5—C6117.55 (14)O2—C1—C2122.47 (13)
C5i—C5—C6120.67 (13)O1—C1—O2121.44 (13)
C5—C6—C7120.27 (14)O3—C2—C1115.84 (14)
N1—C7—C6120.25 (13)O4—C2—C1116.49 (12)
C4—C3—H3120.00O3—C2—O4127.67 (13)
N1—C3—H3120.00
C7—N1—C3—C40.4 (2)C6—C5—C5i—C4i0.3 (2)
C3—N1—C7—C60.3 (2)C6—C5—C5i—C6i180.00 (14)
N1—C3—C4—C50.7 (2)C4—C5—C6—C70.4 (2)
C3—C4—C5—C60.3 (2)C5—C6—C7—N10.7 (2)
C3—C4—C5—C5i179.42 (14)O1—C1—C2—O3179.52 (13)
C5i—C5—C6—C7179.88 (14)O1—C1—C2—O40.7 (2)
C4—C5—C5i—C4i179.98 (16)O2—C1—C2—O31.1 (2)
C4—C5—C5i—C6i0.3 (2)O2—C1—C2—O4178.65 (15)
Symmetry code: (i) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O40.92 (2)2.222 (18)2.6885 (14)110.8 (14)
O1—H1···O4ii0.92 (2)1.81 (2)2.5941 (16)142.5 (16)
N1—H1N···O2iii1.05 (2)2.423 (18)3.0190 (16)114.8 (14)
N1—H1N···O3iii1.05 (2)1.62 (2)2.6359 (18)162.1 (16)
C3—H3···O30.932.473.3498 (18)157
C6—H6···O1iv0.932.373.2291 (18)153
Symmetry codes: (ii) x+1, y, z; (iii) x+2, y+1, z+1; (iv) x1, y, z+1.

Experimental details

Crystal data
Chemical formulaC10H10N22+·2C2HO4
Mr336.26
Crystal system, space groupTriclinic, P1
Temperature (K)150
a, b, c (Å)3.6954 (2), 9.8579 (7), 10.4254 (8)
α, β, γ (°)116.081 (7), 97.214 (5), 97.487 (5)
V3)331.00 (4)
Z1
Radiation typeMo Kα
µ (mm1)0.14
Crystal size (mm)0.3 × 0.2 × 0.1
Data collection
DiffractometerOxford Diffraction KM-4/Xcalibur
diffractometer with a Sapphire3 detector
Absorption correctionMulti-scan
(CrysAlis PRO; Oxford Diffraction, 2006)
Tmin, Tmax0.682, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
2408, 1475, 1134
Rint0.021
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.036, 0.096, 0.99
No. of reflections1475
No. of parameters117
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.27, 0.27

Computer programs: CrysAlis PRO (Oxford Diffraction, 2006), SIR92 (Altomare et al., 1999), PLATON (Spek, 2009) and ORTEP-3 (Farrugia, 1997), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O40.92 (2)2.222 (18)2.6885 (14)110.8 (14)
O1—H1···O4i0.92 (2)1.81 (2)2.5941 (16)142.5 (16)
N1—H1N···O2ii1.05 (2)2.423 (18)3.0190 (16)114.8 (14)
N1—H1N···O3ii1.05 (2)1.62 (2)2.6359 (18)162.1 (16)
C3—H3···O30.932.473.3498 (18)157
C6—H6···O1iii0.932.373.2291 (18)153
Symmetry codes: (i) x+1, y, z; (ii) x+2, y+1, z+1; (iii) x1, y, z+1.
 

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