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The title compound, C5H7N2+·C4H3O4-, crystallizes in space group P21 with one ion pair in the asymmetric unit. The hydrogen maleate anion possesses nearly planar geometry and displays an extremely short intramolecular O-H...O hydrogen bond, with an O...O distance of 2.4198 (19) Å. Classical N-H...O hydrogen bonds, together with short C-H...O contacts, generate an extensive hydrogen-bonding network.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010301727X/sk1655sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010301727X/sk1655Isup2.hkl
Contains datablock I

CCDC reference: 221089

Comment top

The structures of the hydrogen-bonded adducts of polycarboxylic acids with organoamines have received considerable attention in crystal-engineering research (Bowes et al., 2003; Zakaria et al., 2003; Farrell et al., 2002). The maleic acid anion can exist in the fully deprotonated form, or as hydrogen maleate with one of the carboxylic acid groups protonated. Bis(2-aminopyridinium) maleate, 2C5H7N2+·C4H2O42−, has recently been structurally investigated (Büyükgüngör & Odabaşoğlu, 2003). Here, we report the structure of 4-aminopyridinium hydrogen maleate, C5H7N2+·C4H3O4, (I), and compare its hydrogen-bonding interactions with the structure of 2-aminopyridinium maleate. \sch

A view of the ionic pair of (I) with the atomic numbering scheme is depicted in Fig. 1. The hydrogen maleate anion possesses a short intramolecular hydrogen bond with a corresponding O···O distance of 2.4198 (19) Å, which forms a nearly planar seven-membered ring structure, typically found in other hydrogen maleate anions (Madsen & Larsen, 1998, and references therein). The position of the H atom is asymmetrical, with O1—H11 1.17 (3) and O3—H11 1.26 (4) Å. Both cation and anion possess almost planar geometry and are parallel to each other [dihedral angle 1.35 (5)°].

In the structure of (I), the cations and anions are linked together by N—H···O hydrogen bonds. One of the amino-group H atoms forms a contact with one of the O atoms of the neighbouring anion [atom O3(1 − x, y − 1/2, 1 − z)], which is also involved in the formation of an intramolecular hydrogen bond. The second amino-group H atom connects atom N2 with atom O4(x, y − 1, z). The protonated endocyclic pyridine N atom is in contact with atom O2(x − 1,y + 1,z) of the neighbouring anion. One of the hydrogen maleate carboxylate groups is also involved in two short contacts to the pyridine H atoms of two different neighbouring cations, with C3···O1(1 − x, y + 1/2, 1 − z) 3.332 (2) and C6···O2(1 − x, y + 1/2, −z) 3.327 (2) Å. By a combination of classical and non-classical hydrogen-bond interactions, an extensive bonding scheme is created (Fig. 2). Details of the hydrogen bonding are listed in Table 2.

In the structure of bis(2-aminopyridinium) maleate, two eight-membered rings are formed within the asymmetric unit through N—H···O contacts between both carboxylic O atoms and the H atom of the amino group and the H atom on the endocyclic pyridine N atom. The remaining H atom of the amino group in the structure of 2-aminopyridinium maleate is involved in the formation of an intermolecular hydrogen bond with one of the O atoms of the neighbouring maleate ions.

Experimental top

To obtain compound (I), equimolar quantities of of 4-aminopyridine and maleic acid were dissolved in a water solution containing ZnSO4. On standing at room temperature, small colourless crystals of (I) were formed.

Refinement top

All H atoms were found in the Fourier difference map and were freely refined. The value of the Flack parameter [0.4 (9); Flack, 1983] was inconclusive (Flack & Bernardineli, 2000), so the Friedel equivalents were merged prior to the final refinement.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. A view of the ionic pair of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. A packing diagram for (I), showing the hydrogen-bonding contacts as dashed lines.
4-aminopyridinium hydrogen maleate top
Crystal data top
C5H7N2+·C4H3O4F(000) = 220
Mr = 210.19Dx = 1.463 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from all reflections
a = 8.0029 (10) Åθ = 3.0–30.1°
b = 5.4952 (5) ŵ = 0.12 mm1
c = 10.9280 (15) ÅT = 293 K
β = 96.840 (5)°Prismatic, colourless
V = 477.17 (10) Å30.15 × 0.15 × 0.15 mm
Z = 2
Data collection top
Nonius Kappa CCD area-detector
diffractometer
1095 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.017
Graphite monochromatorθmax = 27.1°, θmin = 3.0°
ϕ and ω scansh = 1010
2048 measured reflectionsk = 76
1161 independent reflectionsl = 1413
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.026All H-atom parameters refined
wR(F2) = 0.058 w = 1/[σ2(Fo2) + (0.0207P)2 + 0.0693P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max = 0.001
1161 reflectionsΔρmax = 0.12 e Å3
177 parametersΔρmin = 0.12 e Å3
1 restraintExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.102 (17)
Crystal data top
C5H7N2+·C4H3O4V = 477.17 (10) Å3
Mr = 210.19Z = 2
Monoclinic, P21Mo Kα radiation
a = 8.0029 (10) ŵ = 0.12 mm1
b = 5.4952 (5) ÅT = 293 K
c = 10.9280 (15) Å0.15 × 0.15 × 0.15 mm
β = 96.840 (5)°
Data collection top
Nonius Kappa CCD area-detector
diffractometer
1095 reflections with I > 2σ(I)
2048 measured reflectionsRint = 0.017
1161 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0261 restraint
wR(F2) = 0.058All H-atom parameters refined
S = 1.07Δρmax = 0.12 e Å3
1161 reflectionsΔρmin = 0.12 e Å3
177 parameters
Special details top

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
xyzUiso*/Ueq
O10.82500 (15)0.2172 (3)0.28646 (10)0.0339 (3)
O20.88220 (15)0.4209 (2)0.12172 (11)0.0358 (3)
O30.66709 (16)0.1430 (3)0.32783 (10)0.0396 (4)
O40.50271 (16)0.4149 (3)0.22215 (12)0.0424 (3)
N10.08148 (17)0.2444 (3)0.25554 (14)0.0344 (4)
N20.38411 (18)0.2977 (3)0.41519 (14)0.0325 (4)
C20.1129 (2)0.2320 (4)0.37920 (17)0.0336 (4)
C30.2119 (2)0.0542 (3)0.43560 (15)0.0287 (4)
C40.28488 (18)0.1211 (3)0.36374 (13)0.0249 (4)
C50.24887 (19)0.1019 (3)0.23400 (14)0.0280 (4)
C60.1479 (2)0.0791 (4)0.18459 (15)0.0323 (4)
C110.81397 (18)0.2486 (3)0.16948 (14)0.0269 (3)
C120.7183 (2)0.0718 (4)0.08437 (14)0.0293 (4)
C130.6319 (2)0.1273 (3)0.10700 (15)0.0308 (4)
C140.5973 (2)0.2372 (4)0.22621 (15)0.0308 (4)
H10.009 (3)0.354 (5)0.2214 (18)0.048 (6)*
H20.063 (2)0.359 (4)0.4220 (17)0.039 (5)*
H30.237 (2)0.053 (4)0.5277 (18)0.041 (5)*
H50.295 (2)0.220 (4)0.1830 (16)0.034 (5)*
H60.113 (2)0.095 (4)0.0976 (17)0.037 (5)*
H2A0.435 (3)0.405 (5)0.3649 (19)0.047 (6)*
H2B0.395 (2)0.316 (5)0.500 (2)0.052 (6)*
H110.749 (3)0.048 (7)0.312 (2)0.076 (8)*
H120.721 (2)0.108 (4)0.0017 (17)0.033 (5)*
H130.580 (2)0.218 (5)0.0367 (17)0.041 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0417 (6)0.0348 (8)0.0244 (6)0.0008 (6)0.0001 (5)0.0047 (5)
O20.0412 (7)0.0266 (7)0.0387 (6)0.0083 (6)0.0010 (5)0.0005 (6)
O30.0503 (8)0.0436 (8)0.0256 (6)0.0022 (7)0.0066 (5)0.0065 (6)
O40.0412 (7)0.0347 (7)0.0528 (8)0.0049 (6)0.0117 (6)0.0103 (7)
N10.0294 (7)0.0289 (8)0.0440 (8)0.0007 (7)0.0002 (6)0.0096 (8)
N20.0373 (7)0.0316 (9)0.0288 (7)0.0074 (7)0.0048 (6)0.0021 (6)
C20.0295 (8)0.0284 (9)0.0435 (10)0.0002 (8)0.0070 (7)0.0059 (9)
C30.0293 (8)0.0298 (10)0.0274 (7)0.0017 (7)0.0047 (6)0.0033 (7)
C40.0237 (7)0.0248 (9)0.0262 (7)0.0038 (7)0.0033 (6)0.0009 (7)
C50.0293 (8)0.0305 (9)0.0246 (7)0.0038 (8)0.0051 (6)0.0010 (8)
C60.0306 (8)0.0364 (10)0.0294 (8)0.0084 (8)0.0016 (6)0.0088 (8)
C110.0280 (7)0.0239 (8)0.0286 (7)0.0028 (7)0.0028 (6)0.0011 (7)
C120.0354 (8)0.0303 (9)0.0218 (7)0.0028 (8)0.0024 (6)0.0014 (7)
C130.0359 (8)0.0297 (9)0.0264 (7)0.0051 (7)0.0018 (6)0.0009 (7)
C140.0291 (7)0.0285 (9)0.0357 (8)0.0048 (8)0.0067 (6)0.0060 (8)
Geometric parameters (Å, º) top
O1—C111.2824 (19)N1—H10.88 (2)
O1—H111.17 (3)C2—C31.359 (3)
O2—C111.239 (2)C2—H20.96 (2)
O3—C141.291 (2)C3—C41.412 (2)
O3—H111.26 (4)C3—H31.002 (19)
O4—C141.233 (2)C4—N21.335 (2)
C11—C121.492 (2)C4—C51.417 (2)
C12—C131.333 (3)N2—H2A0.93 (2)
C12—H120.964 (18)N2—H2B0.92 (2)
C13—C141.492 (2)C5—C61.353 (3)
C13—H130.96 (2)C5—H50.96 (2)
N1—C61.344 (3)C6—H60.963 (18)
N1—C21.347 (2)
C11—O1—H11111.5 (12)N1—C2—H2114.5 (11)
C14—O3—H11113.0 (11)C3—C2—H2124.1 (11)
O2—C11—O1122.77 (16)C2—C3—C4119.71 (15)
O2—C11—C12117.00 (13)C2—C3—H3119.7 (13)
O1—C11—C12120.22 (16)C4—C3—H3120.6 (12)
C13—C12—C11131.13 (15)N2—C4—C3121.74 (14)
C13—C12—H12114.9 (13)N2—C4—C5121.04 (16)
C11—C12—H12114.0 (13)C3—C4—C5117.21 (15)
C12—C13—C14130.45 (17)C4—N2—H2A119.4 (13)
C12—C13—H13117.1 (13)C4—N2—H2B118.7 (15)
C14—C13—H13112.4 (13)H2A—N2—H2B122 (2)
O4—C14—O3123.34 (17)C6—C5—C4119.66 (16)
O4—C14—C13117.79 (16)C6—C5—H5121.3 (11)
O3—C14—C13118.86 (17)C4—C5—H5119.0 (11)
C6—N1—C2120.33 (17)N1—C6—C5121.68 (16)
C6—N1—H1119.9 (14)N1—C6—H6114.8 (13)
C2—N1—H1119.5 (14)C5—C6—H6123.5 (13)
N1—C2—C3121.40 (17)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H11···O31.17 (3)1.26 (4)2.4198 (19)174 (2)
N1—H1···O2i0.88 (2)1.87 (2)2.740 (2)168.2 (19)
N2—H2A···O4ii0.93 (2)1.98 (2)2.885 (2)164.2 (19)
N2—H2B···O3iii0.92 (2)2.02 (2)2.9042 (19)160.3 (17)
C3—H3···O1iv1.002 (19)2.49 (2)3.332 (2)141.4 (17)
C6—H6···O2v0.963 (18)2.403 (19)3.327 (2)160.8 (16)
Symmetry codes: (i) x1, y+1, z; (ii) x, y1, z; (iii) x+1, y1/2, z+1; (iv) x+1, y+1/2, z+1; (v) x+1, y+1/2, z.

Experimental details

Crystal data
Chemical formulaC5H7N2+·C4H3O4
Mr210.19
Crystal system, space groupMonoclinic, P21
Temperature (K)293
a, b, c (Å)8.0029 (10), 5.4952 (5), 10.9280 (15)
β (°) 96.840 (5)
V3)477.17 (10)
Z2
Radiation typeMo Kα
µ (mm1)0.12
Crystal size (mm)0.15 × 0.15 × 0.15
Data collection
DiffractometerNonius Kappa CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2048, 1161, 1095
Rint0.017
(sin θ/λ)max1)0.641
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.058, 1.07
No. of reflections1161
No. of parameters177
No. of restraints1
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.12, 0.12

Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), DENZO and SCALEPACK, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97 and PLATON (Spek, 2003).

Selected geometric parameters (Å, º) top
O1—C111.2824 (19)N1—C61.344 (3)
O2—C111.239 (2)N1—C21.347 (2)
O3—C141.291 (2)C2—C31.359 (3)
O4—C141.233 (2)C3—C41.412 (2)
C11—C121.492 (2)C4—N21.335 (2)
C12—C131.333 (3)C4—C51.417 (2)
C13—C141.492 (2)C5—C61.353 (3)
O2—C11—O1122.77 (16)C6—N1—C2120.33 (17)
O2—C11—C12117.00 (13)N1—C2—C3121.40 (17)
O1—C11—C12120.22 (16)C2—C3—C4119.71 (15)
C13—C12—C11131.13 (15)N2—C4—C3121.74 (14)
C12—C13—C14130.45 (17)N2—C4—C5121.04 (16)
O4—C14—O3123.34 (17)C3—C4—C5117.21 (15)
O4—C14—C13117.79 (16)C6—C5—C4119.66 (16)
O3—C14—C13118.86 (17)N1—C6—C5121.68 (16)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H11···O31.17 (3)1.26 (4)2.4198 (19)174 (2)
N1—H1···O2i0.88 (2)1.87 (2)2.740 (2)168.2 (19)
N2—H2A···O4ii0.93 (2)1.98 (2)2.885 (2)164.2 (19)
N2—H2B···O3iii0.92 (2)2.02 (2)2.9042 (19)160.3 (17)
C3—H3···O1iv1.002 (19)2.49 (2)3.332 (2)141.4 (17)
C6—H6···O2v0.963 (18)2.403 (19)3.327 (2)160.8 (16)
Symmetry codes: (i) x1, y+1, z; (ii) x, y1, z; (iii) x+1, y1/2, z+1; (iv) x+1, y+1/2, z+1; (v) x+1, y+1/2, z.
 

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