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Acta Crystallogr Sect E Struct Rep Online. 2009 April 1; 65(Pt 4): o748–o749.
Published online 2009 March 14. doi:  10.1107/S1600536809007247
PMCID: PMC2968938

Bis(4-amino­pyridinium) bis(hydrogen oxalate) monohydrate

Abstract

In the title compound, 2C5H7N2 +·2C2HO4 ·H2O, the asymmetric unit consists of an amino­pyridinium cation, an oxalic actetate anion and a half-molecule of water, which lies on a two-fold rotation axis. The crystal packing is consolidated by inter­molecular O—H(...)O, N—H(...)O and C—H(...)O hydrogen bonds. The mol­ecules are linked into an infinite one dimensional chain along [010].

Related literature

For the biological activity of 4-amino­pyridine, see: Judge & Bever (2006 [triangle]); Schwid et al. (1997 [triangle]); Strupp et al. (2004 [triangle]). For the structure of oxalic acid, see: Derissen & Smith (1974 [triangle]). For related structures, see: Anderson et al. (2005 [triangle]); Bhattacharya et al. (1994 [triangle]); Chao & Schempp (1977 [triangle]); Karle et al. (2003 [triangle]). For stability of the temperature controller, see: Cosier & Glazer (1986 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-0o748-scheme1.jpg

Experimental

Crystal data

  • 2C5H7N2 +·2C2HO4 ·H2O
  • M r = 386.32
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-0o748-efi1.jpg
  • a = 15.6429 (6) Å
  • b = 5.6929 (2) Å
  • c = 19.9091 (7) Å
  • β = 105.617 (2)°
  • V = 1707.52 (11) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.13 mm−1
  • T = 100 K
  • 0.49 × 0.34 × 0.11 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.906, T max = 0.986
  • 12438 measured reflections
  • 2467 independent reflections
  • 2159 reflections with I > 2σ(I)
  • R int = 0.027

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034
  • wR(F 2) = 0.096
  • S = 1.03
  • 2467 reflections
  • 159 parameters
  • All H-atom parameters refined
  • Δρmax = 0.35 e Å−3
  • Δρmin = −0.24 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: SAINT (Bruker, 2005 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809007247/at2732sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809007247/at2732Isup2.hkl

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

Acknowledgments

HKF and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No.1001/PFIZIK/811012.

supplementary crystallographic information

Comment

4-Aminopyridine (Fampridine) is used clinically in Lambert-Eaton myasthenic syndrome and multiple sclerosis because by blocking potassium channels it prolongs action potentials thereby increasing transmitter release at the neuromuscular junction (Judge & Bever, 2006; Schwid et al., 1997; Strupp et al., 2004). The structure of 4-aminopyridine has already been reported (Chao & Schempp, 1977). Redetermination of the structure of 4-aminopyridine has been reported (Anderson et al., 2005). The crystal structure of oxalic acid monohydrate has been reported (Derissen & Smith, 1974). As an extension of our systematic study of the hydrogen bonding patterns of 4-aminopyridine with carboxylic acids, the title compound (I) has been synthesized and the crystal structure determined.

The asymmetric unit of (I) (Fig. 1) contains one molecule of 4-aminopyridine cation, one molecule of oxalate anion and half-a-molecule of water. A proton transfer from the carboxyl group of oxalic acid to atom N1 of 4-aminopyridine resulted in the formation of salts. This protonation lead to the widening of C1–N1–C5 angle of the pyridine ring to 121.0 (8)°, compared to 115.25 (13)° in the unprotonated 4-aminopyridine (Anderson et al., 2005). This type of protonation is observed in various 4-aminopyridine acid complexes (Bhattacharya et al., 1994; Karle et al., 2003). The bond lengths and bond angles of the 4-aminopyridine are comparable to the values reported earlier for 4-aminopyridine (Chao & Schempp, 1977; Anderson et al., 2005). The 4-aminopyridine ring is essentially planar with the maximum deviation from planarity being 0.0075 (9)Å for atom N1. The bond lengths and bond angles of the oxalate are comparable to the values reported for oxalic acid (Derissen & Smith, 1974).

The crystal packing is consolidated by intermolecular O—H···O, N—H···O and C—H···O hydrogen bonds (Table 1). Intermolecular short contacts of O—O = 2.5916 (10)i to 2.7074 (10)Å and N—O = 2.8557 (11)ii to 2.8646 (11)iiiÅ are observed [symmetry codes: (i) x,-1 + y,z; (ii) x,1 - y,1/2 + z; (iii) -1/2 + x,1/2 + y,z]. The molecules are linked into a 3-D network (Fig. 2).

Experimental

Equimolar quantities of 4-aminopyridine (0.094 g, 1 mmol) and oxalic acid (0.090 g, 1 mmol) were dissolved in 25 ml water. The solution was refluxed at 323 K for 12 h. Colourless crystals were harvested after two months of solvent evaporation.

Refinement

All the hydrogen atoms were located from the Fourier map and were allowed to refine freely.

Figures

Fig. 1.
The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme.
Fig. 2.
The crystal packing of the title compound, viewed down the c axis. Dashed lines indicate the hydrogen bonding.

Crystal data

2C5H7N2+·2C2HO4·H2OF(000) = 808
Mr = 386.32Dx = 1.503 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 7009 reflections
a = 15.6429 (6) Åθ = 2.7–38.8°
b = 5.6929 (2) ŵ = 0.13 mm1
c = 19.9091 (7) ÅT = 100 K
β = 105.617 (2)°Plate, colourless
V = 1707.52 (11) Å30.49 × 0.34 × 0.11 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer2467 independent reflections
Radiation source: fine-focus sealed tube2159 reflections with I > 2σ(I)
graphiteRint = 0.027
[var phi] and ω scansθmax = 30.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2005)h = −22→21
Tmin = 0.906, Tmax = 0.986k = −7→7
12438 measured reflectionsl = −27→28

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)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.096All H-atom parameters refined
S = 1.03w = 1/[σ2(Fo2) + (0.0564P)2 + 0.8323P] where P = (Fo2 + 2Fc2)/3
2467 reflections(Δ/σ)max < 0.001
159 parametersΔρmax = 0.35 e Å3
0 restraintsΔρmin = −0.24 e Å3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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
O10.50462 (4)−0.16951 (12)0.39445 (3)0.01643 (15)
O20.59652 (5)−0.02380 (12)0.49260 (3)0.01700 (16)
O30.55682 (5)0.41624 (12)0.44228 (4)0.02023 (17)
O40.45356 (5)0.26647 (12)0.35138 (3)0.01903 (16)
N10.18206 (5)0.86694 (16)0.57611 (4)0.01960 (18)
N20.39056 (6)1.06075 (16)0.74035 (4)0.01829 (17)
C10.20886 (7)0.72101 (18)0.63132 (5)0.0199 (2)
C20.27784 (6)0.77998 (18)0.68707 (5)0.01844 (19)
C30.32276 (6)0.99712 (16)0.68737 (5)0.01467 (18)
C40.29134 (6)1.14587 (17)0.62850 (5)0.01667 (19)
C50.22175 (6)1.07631 (18)0.57489 (5)0.0188 (2)
C60.54297 (6)0.00122 (16)0.43617 (4)0.01357 (17)
C70.51411 (6)0.25017 (16)0.40655 (5)0.01471 (18)
O1W0.50000.46896 (19)0.75000.0215 (2)
H2W10.5135 (12)0.560 (3)0.7190 (9)0.048 (5)*
H10.1765 (9)0.574 (3)0.6285 (7)0.028 (3)*
H20.2966 (9)0.673 (3)0.7268 (8)0.029 (4)*
H40.3195 (9)1.295 (3)0.6250 (7)0.023 (3)*
H50.1983 (9)1.169 (2)0.5344 (7)0.021 (3)*
H1N20.4086 (10)0.968 (3)0.7766 (8)0.028 (4)*
H2N20.4168 (9)1.197 (3)0.7367 (7)0.025 (3)*
H1N10.1413 (11)0.823 (3)0.5397 (9)0.038 (4)*
H1O10.5253 (12)−0.327 (4)0.4140 (9)0.054 (5)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0207 (3)0.0102 (3)0.0151 (3)0.0000 (2)−0.0007 (2)−0.0013 (2)
O20.0197 (3)0.0137 (3)0.0141 (3)0.0009 (2)−0.0014 (3)0.0004 (2)
O30.0259 (4)0.0109 (3)0.0186 (3)−0.0014 (2)−0.0033 (3)−0.0011 (2)
O40.0249 (4)0.0141 (3)0.0136 (3)0.0010 (2)−0.0027 (3)0.0007 (2)
N10.0176 (4)0.0215 (4)0.0160 (4)−0.0005 (3)−0.0017 (3)−0.0030 (3)
N20.0178 (4)0.0182 (4)0.0152 (4)−0.0017 (3)−0.0019 (3)0.0011 (3)
C10.0196 (4)0.0165 (5)0.0221 (5)−0.0023 (3)0.0031 (4)−0.0012 (3)
C20.0192 (4)0.0166 (4)0.0176 (4)−0.0011 (3)0.0017 (3)0.0028 (3)
C30.0149 (4)0.0143 (4)0.0140 (4)0.0012 (3)0.0022 (3)−0.0006 (3)
C40.0177 (4)0.0143 (4)0.0165 (4)0.0008 (3)0.0019 (3)0.0017 (3)
C50.0182 (4)0.0205 (5)0.0152 (4)0.0032 (3)0.0002 (3)0.0025 (3)
C60.0158 (4)0.0112 (4)0.0133 (4)−0.0001 (3)0.0032 (3)−0.0002 (3)
C70.0188 (4)0.0112 (4)0.0132 (4)0.0003 (3)0.0027 (3)0.0002 (3)
O1W0.0307 (6)0.0146 (5)0.0188 (5)0.0000.0061 (4)0.000

Geometric parameters (Å, °)

O1—C61.3139 (11)C1—C21.3654 (13)
O1—H1O11.00 (2)C1—H10.973 (15)
O2—C61.2155 (11)C2—C31.4211 (13)
O3—C71.2611 (11)C2—H20.979 (15)
O4—C71.2458 (11)C3—C41.4221 (12)
N1—C51.3471 (14)C4—C51.3621 (13)
N1—C11.3514 (13)C4—H40.966 (15)
N1—H1N10.863 (17)C5—H50.951 (13)
N2—C31.3291 (12)C6—C71.5547 (13)
N2—H1N20.877 (15)O1W—H2W10.874 (18)
N2—H2N20.890 (16)
C6—O1—H1O1111.9 (11)N2—C3—C4121.12 (9)
C5—N1—C1121.00 (8)C2—C3—C4116.98 (8)
C5—N1—H1N1118.7 (11)C5—C4—C3119.91 (9)
C1—N1—H1N1120.2 (11)C5—C4—H4118.8 (8)
C3—N2—H1N2120.1 (10)C3—C4—H4121.3 (8)
C3—N2—H2N2117.4 (9)N1—C5—C4121.21 (9)
H1N2—N2—H2N2122.5 (13)N1—C5—H5115.6 (8)
N1—C1—C2120.95 (9)C4—C5—H5123.2 (9)
N1—C1—H1116.1 (8)O2—C6—O1125.55 (8)
C2—C1—H1123.0 (8)O2—C6—C7121.00 (8)
C1—C2—C3119.93 (9)O1—C6—C7113.45 (7)
C1—C2—H2120.2 (9)O4—C7—O3127.09 (8)
C3—C2—H2119.9 (9)O4—C7—C6118.46 (8)
N2—C3—C2121.90 (9)O3—C7—C6114.44 (8)
C5—N1—C1—C2−0.98 (15)C1—N1—C5—C41.41 (15)
N1—C1—C2—C3−0.29 (15)C3—C4—C5—N1−0.56 (15)
C1—C2—C3—N2−179.57 (9)O2—C6—C7—O4−173.95 (8)
C1—C2—C3—C41.08 (14)O1—C6—C7—O46.47 (12)
N2—C3—C4—C5179.98 (9)O2—C6—C7—O36.58 (13)
C2—C3—C4—C5−0.67 (14)O1—C6—C7—O3−173.00 (8)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1W—H2W1···O4i0.874 (18)1.895 (18)2.7676 (9)175.0 (18)
N2—H1N2···O4ii0.877 (15)1.983 (16)2.8556 (11)173.4 (14)
N2—H2N2···O1Wiii0.890 (16)1.993 (15)2.8620 (12)164.8 (13)
N1—H1N1···O3iv0.863 (17)2.100 (17)2.8645 (11)147.3 (15)
N1—H1N1···O2iv0.863 (17)2.218 (17)2.8818 (11)133.6 (15)
O1—H1O1···O3v1.00 (2)1.60 (2)2.5916 (10)177.6 (18)
C5—H5···O2vi0.951 (13)2.361 (14)3.1585 (12)141.2 (11)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2732).

References

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