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Ethyl­ammonium hydrogen oxalate–oxalic acid (2/1)

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aLaboratoire de Chimie Minérale et Analytique (LACHIMIA), Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal, and bICMUB UMR 6302, Université de Bourgogne, Faculté des Sciences, 9 avenue Alain Savary, 21000 DIJON, France
*Correspondence e-mail: dlibasse@gmail.com

Edited by R. J. Butcher, Howard University, USA (Received 30 March 2019; accepted 4 May 2019; online 14 May 2019)

The reaction between ethyl­amine and oxalic acid in water in a 1:1 molar ratio afforded the title salt, C2H8N+·C2HO4·0.5C2H2O4. The hydrogen oxalate anions inter­act through hydrogen bonding and are organized into a chains propagating along the c-axis direction. The chains are connected to the neighbouring cations and oxalic acid mol­ecules by N—H⋯O and O—H⋯O hydrogen bonds and N⋯O dipole–dipole contacts, leading to a supra­molecular three-dimensional network.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Ammonium carboxyl­ate networks obtained by mixing di­carb­oxy­lic acids with amines is of inter­est in the field of crystal engineering (Ballabh et al. 2002[Ballabh, A., Trivedi, D. D., Dastidar, P. & Suresh, E. (2002). CrystEngComm, 4, 135-142.]; Haynes & Pietersen, 2008[Haynes, D. A. & Pietersen, L. K. (2008). CrystEngComm, 10, 518-524.]; Dziuk et al. 2014a[Dziuk, B., Ejsmont, K. & Zaleski, J. (2014a). CHEMIK, 68, 391-395.]). These compounds exhibit a variety of structures that can lead, through non-covalent inter­actions (hydrogen bonding, ππ stacking, van der Waals and C—H⋯π contacts), to a large diversity of architectures and topologies. Di­carb­oxy­lic acids can act as polydirectional synthons, and amines, via the formation of ammonium, greatly increase the possible of linkages and inter­actions (Ivasenko & Perepichka, 2011[Ivasenko, O. & Perepichka, D. F. (2011). Chem. Soc. Rev. 40, 191-206.]; Yuge et al., 2008[Yuge, T., Sakai, T., Kai, N., Hisaki, I., Miyata, M. & Tohnai, N. (2008). Chem. Eur. J. 14, 2984-2993.]; Lemmerer, 2011[Lemmerer, A. (2011). Cryst. Growth Des. 11, 583-593.]). To date, many examples of such crystalline networks from oxalic acid and hydrogen oxalate have been described, see for example: Dziuk et al. (2014b[Dziuk, B., Zarychta, B. & Ejsmont, K. (2014b). Acta Cryst. E70, o852.],c[Dziuk, B., Zarychta, B. & Ejsmont, K. (2014c). Acta Cryst. E70, o917-o918.]); Braga et al. (2013[Braga, D., Chelazzi, L., Ciabatti, I. & Grepionoi, F. (2013). New J. Chem. 37, 97-104.]); Ejsmont (2006[Ejsmont, K. (2006). Acta Cryst. E62, o5852-o5854.], 2007[Ejsmont, K. (2007). Acta Cryst. E63, o107-o109.]); Ejsmont & Zaleski (2006a[Ejsmont, K. & Zaleski, J. (2006a). Acta Cryst. E62, o3879-o3880.],b[Ejsmont, K. & Zaleski, J. (2006b). Acta Cryst. E62, o2512-o2513.]); MacDonald et al. (2001[MacDonald, J. C., Dorrestein, P. C. & Pilley, M. M. (2001). Cryst. Growth Des. 1, 29-38.]). Our group has also contributed to this area by reporting recently two new structures of such compounds (Diallo et al., 2015[Diallo, W., Gueye, N., Crochet, A., Plasseraud, L. & Cattey, H. (2015). Acta Cryst. E71, 473-475.]; Diop et al., 2016[Diop, M. B., Diop, L., Plasseraud, L. & Cattey, H. (2016). Acta Cryst. E72, 1113-1115.]). In a continuation of this work, we describe herein the synthesis and structure of the title salt I, isolated from an equimolar mixture of oxalic acid and ethyl­amine.

Compound I crystallizes in the monoclinic C2/c space group with the asymmetric unit comprising of one ethyl­ammonium cation (C2H8N+), one hydrogen oxalate anion (C2HO4) and a half-mol­ecule of oxalic acid (C2H2O4). The three components are linked together by several inter­molecular inter­actions (Table 1[link] and Fig. 1[link]). The inter­atomic distances and angles of the ethyl­ammonium cation are in the range of those previously measured for comparable salts (Ejsmont & Zaleski, 2006a[Ejsmont, K. & Zaleski, J. (2006a). Acta Cryst. E62, o3879-o3880.]; Ejsmont, 2006[Ejsmont, K. (2006). Acta Cryst. E62, o5852-o5854.]). Each C2H8N+ cation is involved in N—H⋯O hydrogen bonding with two distinct C2HO4 anions [N—HA⋯O4 = 2.8472 (11) and N—HB⋯O1 = 2.9409 (11) Å] and also with one neutral C2H2O4 mol­ecule [N—HC⋯O6 = 3.0400 (10) Å]. These inter­actions are reinforced by van der Waals contacts involving C2H8N+, and C2HO4 and C2H2O4, respectively [N⋯O3 = 2.8960 (11) and N⋯O5 = 2.9423 (11) Å]. The hydrogen oxalate anion is twisted with an O3—C2—C1—O2 torsion angle of 168.94 (8)°. The C—C and C—O bond distances [C1—C2 = 1.5570 (13), C1—O1 = 1.2141 (12), C1—O2 = 1.3090 (11), C2—O3 = 1.2415 (11), C2—O4 = 1.2565 (12) Å] are similar to those observed in the literature for other organic salts containing this anion (Barnes, 2003[Barnes, J. C. (2003). Acta Cryst. E59, o931-o933.]; Essid et al., 2013[Essid, M., Marouani, H., Al-Deyab, S. S. & Rzaigui, M. (2013). Acta Cryst. E69, o1279.]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O2—H2⋯O3i 0.84 1.74 2.5717 (9) 173
N—HA⋯O4 0.91 1.94 2.8472 (11) 177
N—HB⋯O1ii 0.91 2.04 2.9409 (11) 172
N—HC⋯O6iii 0.91 2.16 3.0400 (10) 163
O5—H5⋯O4 0.84 1.68 2.5139 (10) 173
Symmetry codes: (i) [x, -y, z+{\script{1\over 2}}]; (ii) [-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]; (iii) [-x+1, y, -z+{\script{1\over 2}}].
[Figure 1]
Figure 1
View of the title salt showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dotted lines [symmetry codes: (i) x, −y, [{1\over 2}] + z; (ii) 1 − x, −y, 1 − z; (iii) 1 − x, y, [{1\over 2}] − z; (iv): [{3\over 2}] − x, −[{1\over 2}] + y, [{1\over 2}] − z].

The hydrogen oxalate anions in I are linked into chains running parallel to the c axis by O2—H2⋯O3 hydrogen bonds [2.5717 (9) Å]. Adjacent chains are bridged by neutral oxalic acid mol­ecules whose two OH groups participate in hydrogen-bonding inter­actions with two distinct hydrogen oxalate anions [O5—H5⋯O4 = 2.5139 (10) Å], resulting in the formation of sheets. These sheets are stacked along the b axis with the ethyl­ammonium cations inter­calated between the sheets, generating a three-dimensional network (Fig. 2[link]).

[Figure 2]
Figure 2
The packing, viewed along the c axis, showing the inter­molecular hydrogen-bonding scheme (dashed lines) [colour code: C dark grey, H white, O red, N blue].

A search on the online portal of the Cambridge Structural Database (WebCSD; Thomas et al., 2010[Thomas, I. R., Bruno, I. J., Cole, J. C., Macrae, C. F., Pidcock, E. & Wood, P. A. (2010). J. Appl. Cryst. 43, 362-366.]) yielded 188 hits for ethyl­ammonium salts and 25 hits for the hydrogen oxalate–oxalic acid combination.

Synthesis and crystallization

All the chemicals were purchased from Aldrich (Germany) and used without further purification. The title compound was obtained by reacting equimolar amounts of oxalic acid (1.26 g, 0.02 mol) and ethyl­amine (50% in water, 2.6 ml, 0.02 mol), in 25 ml of water at 298 K. The resulting solution was allowed to evaporate at 338 K, leading after few days to colourless prismatic suitable for X-ray analysis.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C2H8N+·C2HO4·0.5C2H2O4
Mr 360.28
Crystal system, space group Monoclinic, C2/c
Temperature (K) 100
a, b, c (Å) 21.1667 (8), 6.6243 (3), 11.3247 (4)
β (°) 91.509 (2)
V3) 1587.34 (11)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.14
Crystal size (mm) 0.47 × 0.3 × 0.17
 
Data collection
Diffractometer Bruker D8 Venture triumph Mo
Absorption correction Multi-scan (SADABS; Bruker, 2014[Bruker (2014). APEX3, SADABS and SAINT. Bruker AXS Inc, Madison, Wisconsin, USA.])
Tmin, Tmax 0.712, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 14201, 1829, 1624
Rint 0.027
(sin θ/λ)max−1) 0.650
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.075, 1.03
No. of reflections 1829
No. of parameters 113
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.50, −0.20
Computer programs: APEX3 and SAINT (Bruker, 2014[Bruker (2014). APEX3, SADABS and SAINT. Bruker AXS Inc, Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Structural data


Computing details top

Data collection: APEX3 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Ethylammonium hydrogen oxalate–oxalic acid (2/1) top
Crystal data top
C2H8N+·C2HO4·0.5C2H2O4F(000) = 760
Mr = 360.28Dx = 1.508 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 21.1667 (8) ÅCell parameters from 7758 reflections
b = 6.6243 (3) Åθ = 3.2–27.5°
c = 11.3247 (4) ŵ = 0.14 mm1
β = 91.509 (2)°T = 100 K
V = 1587.34 (11) Å3Prism, colourless
Z = 40.47 × 0.3 × 0.17 mm
Data collection top
Bruker D8 Venture triumph Mo
diffractometer
1829 independent reflections
Radiation source: X-ray tube, Siemens KFF Mo 2K-90C1624 reflections with I > 2σ(I)
TRIUMPH curved crystal monochromatorRint = 0.027
Detector resolution: 1024 x 1024 pixels mm-1θmax = 27.5°, θmin = 3.2°
φ and ω scans'h = 2727
Absorption correction: multi-scan
(SADABS; Bruker, 2014)
k = 88
Tmin = 0.712, Tmax = 0.746l = 1413
14201 measured reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.028H-atom parameters constrained
wR(F2) = 0.075 w = 1/[σ2(Fo2) + (0.0383P)2 + 1.1891P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.001
1829 reflectionsΔρmax = 0.50 e Å3
113 parametersΔρmin = 0.20 e Å3
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H = 0.99 Å (ethyl group) with Uiso(H) = 1.2Ueq(C) or O—H = 0.84 Å (hydroxyl), N—H = 0.91 Å (ammonium) and C—H = 0.98 Å (methyl group) with Uiso(H) = 1.5Ueq(O or N or C).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.75227 (4)0.01386 (14)0.48767 (8)0.01041 (19)
O10.80530 (3)0.07888 (11)0.50554 (6)0.01374 (16)
C20.72301 (4)0.00320 (14)0.36024 (8)0.01042 (19)
O20.71415 (3)0.05216 (11)0.56824 (6)0.01410 (17)
H20.7313110.0376170.6354300.021*
O30.76073 (3)0.03334 (11)0.28000 (6)0.01506 (17)
O40.66506 (3)0.03493 (11)0.34790 (6)0.01416 (17)
N0.61063 (4)0.32342 (12)0.18905 (7)0.01222 (18)
HA0.6268270.2307480.2408650.018*
HB0.6398500.3526370.1340660.018*
HC0.5753040.2723530.1525450.018*
C40.59405 (5)0.51142 (15)0.25420 (9)0.0146 (2)
H4A0.6306460.5553350.3040260.018*
H4B0.5583070.4840250.3065320.018*
C50.57599 (5)0.67710 (16)0.16787 (10)0.0199 (2)
H5A0.6121350.7085620.1187680.030*
H5B0.5637190.7980670.2114910.030*
H5C0.5404060.6320350.1173910.030*
C30.52681 (4)0.03067 (14)0.45853 (8)0.0111 (2)
O50.57859 (3)0.06835 (11)0.48337 (6)0.01553 (17)
H50.6077610.0252390.4412750.023*
O60.51865 (3)0.15638 (11)0.38186 (6)0.01596 (17)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0115 (4)0.0107 (4)0.0091 (4)0.0012 (3)0.0008 (3)0.0006 (3)
O10.0110 (3)0.0190 (4)0.0111 (3)0.0022 (3)0.0007 (2)0.0001 (3)
C20.0111 (4)0.0109 (4)0.0092 (4)0.0000 (3)0.0002 (3)0.0009 (3)
O20.0135 (3)0.0212 (4)0.0076 (3)0.0033 (3)0.0003 (3)0.0010 (3)
O30.0112 (3)0.0251 (4)0.0090 (3)0.0026 (3)0.0014 (2)0.0004 (3)
O40.0094 (3)0.0218 (4)0.0113 (3)0.0026 (3)0.0007 (2)0.0037 (3)
N0.0109 (4)0.0143 (4)0.0114 (4)0.0009 (3)0.0008 (3)0.0014 (3)
C40.0131 (5)0.0162 (5)0.0145 (5)0.0005 (4)0.0012 (4)0.0009 (4)
C50.0187 (5)0.0164 (5)0.0247 (5)0.0010 (4)0.0022 (4)0.0048 (4)
C30.0102 (4)0.0130 (4)0.0100 (4)0.0011 (3)0.0003 (3)0.0016 (3)
O50.0095 (3)0.0216 (4)0.0157 (4)0.0027 (3)0.0040 (3)0.0060 (3)
O60.0126 (3)0.0202 (4)0.0152 (4)0.0001 (3)0.0012 (3)0.0064 (3)
Geometric parameters (Å, º) top
C1—O11.2141 (12)C4—H4A0.9900
C1—C21.5570 (13)C4—H4B0.9900
C1—O21.3090 (11)C4—C51.5122 (14)
C2—O31.2415 (11)C5—H5A0.9800
C2—O41.2565 (12)C5—H5B0.9800
O2—H20.8400C5—H5C0.9800
N—HA0.9100C3—C3i1.5467 (18)
N—HB0.9100C3—O51.3016 (12)
N—HC0.9100C3—O61.2121 (12)
N—C41.4940 (12)O5—H50.8400
O1—C1—C2120.93 (8)N—C4—C5110.14 (8)
O1—C1—O2125.90 (9)H4A—C4—H4B108.1
O2—C1—C2113.17 (8)C5—C4—H4A109.6
O3—C2—C1115.04 (8)C5—C4—H4B109.6
O3—C2—O4126.56 (9)C4—C5—H5A109.5
O4—C2—C1118.40 (8)C4—C5—H5B109.5
C1—O2—H2109.5C4—C5—H5C109.5
HA—N—HB109.5H5A—C5—H5B109.5
HA—N—HC109.5H5A—C5—H5C109.5
HB—N—HC109.5H5B—C5—H5C109.5
C4—N—HA109.5O5—C3—C3i111.32 (10)
C4—N—HB109.5O6—C3—C3i121.50 (11)
C4—N—HC109.5O6—C3—O5127.18 (9)
N—C4—H4A109.6C3—O5—H5109.5
N—C4—H4B109.6
O1—C1—C2—O311.28 (13)O2—C1—C2—O3168.94 (8)
O1—C1—C2—O4169.03 (9)O2—C1—C2—O410.75 (12)
Symmetry code: (i) x+1, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O3ii0.841.742.5717 (9)173
N—HA···O40.911.942.8472 (11)177
N—HB···O1iii0.912.042.9409 (11)172
N—HC···O6iv0.912.163.0400 (10)163
O5—H5···O40.841.682.5139 (10)173
Symmetry codes: (ii) x, y, z+1/2; (iii) x+3/2, y+1/2, z+1/2; (iv) x+1, y, z+1/2.
 

Acknowledgements

The authors gratefully acknowledge the Cheikh Anta Diop University of Dakar (Senegal), the Centre National de la Recherche Scientifique (CNRS, France) and the University of Bourgogne Franche-Comté (Dijon, France) for support.

References

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