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

Fun, H.-K.; John, J.; Jebas, S.R.; Balasubramanian, T.

doi:10.1107/S1600536809007247

organic compounds

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ISSN: 2056-9890

Volume 65| Part 4| April 2009| Pages o748-o749

doi:10.1107/S1600536809007247

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

Hoong-Kun Fun,^a ^* Jain John,^b Samuel Robinson Jebas ^a ‡ and T Balasubramanian ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bDepartment of Physics, National Institute of Technology, Tiruchirappalli 620015, India
^*Correspondence e-mail: hkfun@usm.my

(Received 25 February 2009; accepted 27 February 2009; online 14 March 2009)

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 ); Schwid et al. (1997 ); Strupp et al. (2004 ). For the structure of oxalic acid, see: Derissen & Smith (1974 ). For related structures, see: Anderson et al. (2005 ); Bhattacharya et al. (1994 ); Chao & Schempp (1977 ); Karle et al. (2003 ). For stability of the temperature controller, see: Cosier & Glazer (1986 ).

Experimental

Crystal data

2C₅H₇N₂⁺·2C₂HO₄⁻·H₂O
M_r = 386.32
Monoclinic, C 2/c
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 ) 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[F² > 2σ(F²)] = 0.034
wR(F²) = 0.096
S = 1.03
2467 reflections
159 parameters
All H-atom parameters refined
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H2W1⋯O4ⁱ	0.874 (18)	1.895 (18)	2.7676 (9)	175.0 (18)
N2—H1N2⋯O4ⁱⁱ	0.877 (15)	1.983 (16)	2.8556 (11)	173.4 (14)
N2—H2N2⋯O1Wⁱⁱⁱ	0.890 (16)	1.993 (15)	2.8620 (12)	164.8 (13)
N1—H1N1⋯O3^iv	0.863 (17)	2.100 (17)	2.8645 (11)	147.3 (15)
N1—H1N1⋯O2^iv	0.863 (17)	2.218 (17)	2.8818 (11)	133.6 (15)
O1—H1O1⋯O3^v	1.00 (2)	1.60 (2)	2.5916 (10)	177.6 (18)
C5—H5⋯O2^vi	0.951 (13)	2.361 (14)	3.1585 (12)	141.2 (11)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) $[x, -y+1, z+{\script{1\over 2}}]$ ; (iii) x, y+1, z; (iv) $[x-{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (v) x, y-1, z; (vi) $[x-{\script{1\over 2}}, y+{\script{3\over 2}}, z]$ .

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

Supporting information

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

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

checkCIF report

Comment top

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).

Related literature top

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

Experimental top

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.

Computing details top

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

Figures top

	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.

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

Crystal data top

2C₅H₇N₂⁺·2C₂HO₄⁻·H₂O	F(000) = 808
M_r = 386.32	D_x = 1.503 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 7009 reflections
a = 15.6429 (6) Å	θ = 2.7–38.8°
b = 5.6929 (2) Å	µ = 0.13 mm⁻¹
c = 19.9091 (7) Å	T = 100 K
β = 105.617 (2)°	Plate, colourless
V = 1707.52 (11) Å³	0.49 × 0.34 × 0.11 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2467 independent reflections
Radiation source: fine-focus sealed tube	2159 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.027
ϕ and ω scans	θ_max = 30.0°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −22→21
T_min = 0.906, T_max = 0.986	k = −7→7
12438 measured reflections	l = −27→28

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.096	All H-atom parameters refined
S = 1.03	w = 1/[σ²(F_o²) + (0.0564P)² + 0.8323P] where P = (F_o² + 2F_c²)/3
2467 reflections	(Δ/σ)_max < 0.001
159 parameters	Δρ_max = 0.35 e Å⁻³
0 restraints	Δρ_min = −0.24 e Å⁻³

Crystal data top

2C₅H₇N₂⁺·2C₂HO₄⁻·H₂O	V = 1707.52 (11) Å³
M_r = 386.32	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 15.6429 (6) Å	µ = 0.13 mm⁻¹
b = 5.6929 (2) Å	T = 100 K
c = 19.9091 (7) Å	0.49 × 0.34 × 0.11 mm
β = 105.617 (2)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2467 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2159 reflections with I > 2σ(I)
T_min = 0.906, T_max = 0.986	R_int = 0.027
12438 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	0 restraints
wR(F²) = 0.096	All H-atom parameters refined
S = 1.03	Δρ_max = 0.35 e Å⁻³
2467 reflections	Δρ_min = −0.24 e Å⁻³
159 parameters

Special details top

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) top

	x	y	z	U_iso*/U_eq
O1	0.50462 (4)	−0.16951 (12)	0.39445 (3)	0.01643 (15)
O2	0.59652 (5)	−0.02380 (12)	0.49260 (3)	0.01700 (16)
O3	0.55682 (5)	0.41624 (12)	0.44228 (4)	0.02023 (17)
O4	0.45356 (5)	0.26647 (12)	0.35138 (3)	0.01903 (16)
N1	0.18206 (5)	0.86694 (16)	0.57611 (4)	0.01960 (18)
N2	0.39056 (6)	1.06075 (16)	0.74035 (4)	0.01829 (17)
C1	0.20886 (7)	0.72101 (18)	0.63132 (5)	0.0199 (2)
C2	0.27784 (6)	0.77998 (18)	0.68707 (5)	0.01844 (19)
C3	0.32276 (6)	0.99712 (16)	0.68737 (5)	0.01467 (18)
C4	0.29134 (6)	1.14587 (17)	0.62850 (5)	0.01667 (19)
C5	0.22175 (6)	1.07631 (18)	0.57489 (5)	0.0188 (2)
C6	0.54297 (6)	0.00122 (16)	0.43617 (4)	0.01357 (17)
C7	0.51411 (6)	0.25017 (16)	0.40655 (5)	0.01471 (18)
O1W	0.5000	0.46896 (19)	0.7500	0.0215 (2)
H2W1	0.5135 (12)	0.560 (3)	0.7190 (9)	0.048 (5)*
H1	0.1765 (9)	0.574 (3)	0.6285 (7)	0.028 (3)*
H2	0.2966 (9)	0.673 (3)	0.7268 (8)	0.029 (4)*
H4	0.3195 (9)	1.295 (3)	0.6250 (7)	0.023 (3)*
H5	0.1983 (9)	1.169 (2)	0.5344 (7)	0.021 (3)*
H1N2	0.4086 (10)	0.968 (3)	0.7766 (8)	0.028 (4)*
H2N2	0.4168 (9)	1.197 (3)	0.7367 (7)	0.025 (3)*
H1N1	0.1413 (11)	0.823 (3)	0.5397 (9)	0.038 (4)*
H1O1	0.5253 (12)	−0.327 (4)	0.4140 (9)	0.054 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0207 (3)	0.0102 (3)	0.0151 (3)	0.0000 (2)	−0.0007 (2)	−0.0013 (2)
O2	0.0197 (3)	0.0137 (3)	0.0141 (3)	0.0009 (2)	−0.0014 (3)	0.0004 (2)
O3	0.0259 (4)	0.0109 (3)	0.0186 (3)	−0.0014 (2)	−0.0033 (3)	−0.0011 (2)
O4	0.0249 (4)	0.0141 (3)	0.0136 (3)	0.0010 (2)	−0.0027 (3)	0.0007 (2)
N1	0.0176 (4)	0.0215 (4)	0.0160 (4)	−0.0005 (3)	−0.0017 (3)	−0.0030 (3)
N2	0.0178 (4)	0.0182 (4)	0.0152 (4)	−0.0017 (3)	−0.0019 (3)	0.0011 (3)
C1	0.0196 (4)	0.0165 (5)	0.0221 (5)	−0.0023 (3)	0.0031 (4)	−0.0012 (3)
C2	0.0192 (4)	0.0166 (4)	0.0176 (4)	−0.0011 (3)	0.0017 (3)	0.0028 (3)
C3	0.0149 (4)	0.0143 (4)	0.0140 (4)	0.0012 (3)	0.0022 (3)	−0.0006 (3)
C4	0.0177 (4)	0.0143 (4)	0.0165 (4)	0.0008 (3)	0.0019 (3)	0.0017 (3)
C5	0.0182 (4)	0.0205 (5)	0.0152 (4)	0.0032 (3)	0.0002 (3)	0.0025 (3)
C6	0.0158 (4)	0.0112 (4)	0.0133 (4)	−0.0001 (3)	0.0032 (3)	−0.0002 (3)
C7	0.0188 (4)	0.0112 (4)	0.0132 (4)	0.0003 (3)	0.0027 (3)	0.0002 (3)
O1W	0.0307 (6)	0.0146 (5)	0.0188 (5)	0.000	0.0061 (4)	0.000

Geometric parameters (Å, º) top

O1—C6	1.3139 (11)	C1—C2	1.3654 (13)
O1—H1O1	1.00 (2)	C1—H1	0.973 (15)
O2—C6	1.2155 (11)	C2—C3	1.4211 (13)
O3—C7	1.2611 (11)	C2—H2	0.979 (15)
O4—C7	1.2458 (11)	C3—C4	1.4221 (12)
N1—C5	1.3471 (14)	C4—C5	1.3621 (13)
N1—C1	1.3514 (13)	C4—H4	0.966 (15)
N1—H1N1	0.863 (17)	C5—H5	0.951 (13)
N2—C3	1.3291 (12)	C6—C7	1.5547 (13)
N2—H1N2	0.877 (15)	O1W—H2W1	0.874 (18)
N2—H2N2	0.890 (16)

C6—O1—H1O1	111.9 (11)	N2—C3—C4	121.12 (9)
C5—N1—C1	121.00 (8)	C2—C3—C4	116.98 (8)
C5—N1—H1N1	118.7 (11)	C5—C4—C3	119.91 (9)
C1—N1—H1N1	120.2 (11)	C5—C4—H4	118.8 (8)
C3—N2—H1N2	120.1 (10)	C3—C4—H4	121.3 (8)
C3—N2—H2N2	117.4 (9)	N1—C5—C4	121.21 (9)
H1N2—N2—H2N2	122.5 (13)	N1—C5—H5	115.6 (8)
N1—C1—C2	120.95 (9)	C4—C5—H5	123.2 (9)
N1—C1—H1	116.1 (8)	O2—C6—O1	125.55 (8)
C2—C1—H1	123.0 (8)	O2—C6—C7	121.00 (8)
C1—C2—C3	119.93 (9)	O1—C6—C7	113.45 (7)
C1—C2—H2	120.2 (9)	O4—C7—O3	127.09 (8)
C3—C2—H2	119.9 (9)	O4—C7—C6	118.46 (8)
N2—C3—C2	121.90 (9)	O3—C7—C6	114.44 (8)

C5—N1—C1—C2	−0.98 (15)	C1—N1—C5—C4	1.41 (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—C4	1.08 (14)	O1—C6—C7—O4	6.47 (12)
N2—C3—C4—C5	179.98 (9)	O2—C6—C7—O3	6.58 (13)
C2—C3—C4—C5	−0.67 (14)	O1—C6—C7—O3	−173.00 (8)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H2W1···O4ⁱ	0.874 (18)	1.895 (18)	2.7676 (9)	175.0 (18)
N2—H1N2···O4ⁱⁱ	0.877 (15)	1.983 (16)	2.8556 (11)	173.4 (14)
N2—H2N2···O1Wⁱⁱⁱ	0.890 (16)	1.993 (15)	2.8620 (12)	164.8 (13)
N1—H1N1···O3^iv	0.863 (17)	2.100 (17)	2.8645 (11)	147.3 (15)
N1—H1N1···O2^iv	0.863 (17)	2.218 (17)	2.8818 (11)	133.6 (15)
O1—H1O1···O3^v	1.00 (2)	1.60 (2)	2.5916 (10)	177.6 (18)
C5—H5···O2^vi	0.951 (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.

Experimental details

Crystal data
Chemical formula	2C₅H₇N₂⁺·2C₂HO₄⁻·H₂O
M_r	386.32
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	100
a, b, c (Å)	15.6429 (6), 5.6929 (2), 19.9091 (7)
β (°)	105.617 (2)
V (Å³)	1707.52 (11)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.13
Crystal size (mm)	0.49 × 0.34 × 0.11

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.906, 0.986
No. of measured, independent and observed [I > 2σ(I)] reflections	12438, 2467, 2159
R_int	0.027
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.096, 1.03
No. of reflections	2467
No. of parameters	159
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.35, −0.24

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H2W1···O4ⁱ	0.874 (18)	1.895 (18)	2.7676 (9)	175.0 (18)
N2—H1N2···O4ⁱⁱ	0.877 (15)	1.983 (16)	2.8556 (11)	173.4 (14)
N2—H2N2···O1Wⁱⁱⁱ	0.890 (16)	1.993 (15)	2.8620 (12)	164.8 (13)
N1—H1N1···O3^iv	0.863 (17)	2.100 (17)	2.8645 (11)	147.3 (15)
N1—H1N1···O2^iv	0.863 (17)	2.218 (17)	2.8818 (11)	133.6 (15)
O1—H1O1···O3^v	1.00 (2)	1.60 (2)	2.5916 (10)	177.6 (18)
C5—H5···O2^vi	0.951 (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

‡Permanent address: Department of Physics, Karunya University, Karunya Nagar, Coimbatore 641114, India.

Acknowledgements

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.

References

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