1H-Pyrazol-2-ium hydrogen oxalate

Abstract

In the title compound, C₃H₅N₂ ⁺·C₂HO₄ ⁻, the anions form centrosymmetric dimers through cyclic O—H⋯O hydrogen-bonding associations [graph set R ₂ ²(10)]. These dimers are then linked through a cyclic R ₄ ²(10) N—H⋯O hydrogen-bonding association involving two cations and the carboxyl O-atom acceptors of separate anions, giving chain structures extending across the (111) plane.

Related literature  

For general background to ferroelectric organic frameworks, see: Fu et al. (2009 ▶); Ye et al. (2006 ▶); Zhang et al. (2008 ▶, 2010 ▶). For graph-set analysis, see: Etter et al. (1990 ▶).

Experimental  

Crystal data  

• C₃H₅N₂ ⁺·C₂HO₄ ⁻

• M _r = 158.12

• Triclinic,

• a = 3.7286 (7) Å

• b = 9.836 (2) Å

• c = 10.487 (2) Å

• α = 117.35 (3)°

• β = 97.01 (3)°

• γ = 93.65 (3)°

• V = 335.92 (14) ų

• Z = 2

• Mo Kα radiation

• μ = 0.14 mm⁻¹

• T = 293 K

• 0.26 × 0.22 × 0.14 mm

Data collection  

• Rigaku SCXmini CCD diffractometer

• Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 ▶) T _min = 0.965, T _max = 0.993

• 3484 measured reflections

• 1527 independent reflections

• 702 reflections with I > 2σ(I)

• R _int = 0.063

Refinement  

• R[F ² > 2σ(F ²)] = 0.095

• wR(F ²) = 0.285

• S = 1.07

• 1527 reflections

• 101 parameters

• H-atom parameters constrained

• Δρ_max = 0.48 e Å⁻³

• Δρ_min = −0.29 e Å⁻³

Data collection: CrystalClear (Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Supplementary material file. DOI: 10.1107/S1600536812023136/zs2209Isup3.cml

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O1i	0.86	1.86	2.709 (5)	170
N2—H2A⋯O1ii	0.86	1.92	2.715 (5)	153
O4—H4⋯O3iii	0.82	1.95	2.679 (5)	147

Symmetry codes: (i) ; (ii) ; (iii) .

supplementary crystallographic information

Comment

As a contribution to a search for new ferroelectric materials (Fu et al., 2009; Ye et al., 2006; Zhang et al., 2008, 2010), we have synthesized the title salt, C₃H₅N₂⁺. C₂HO₄^- from a 1:1 stoichiometric reaction of pyrazole with oxalic acid and the structure is reported here.

In the structure of the title compound (Fig.1) the molecules are organized in a one-dimensional chain structure involving both inter-anionic and cation–anion hydrogen-bonding associations (Table 1). The anions form centrosymmetric dimers through cyclic O—H···O hydrogen-bonding associations [graph set R²₂(10) (Etter et al., 1990)]. These dimers are then linked through a cyclic R²₄(10) N—H···O hydrogen-bonding association involving two cations and the carboxyl O-atom acceptors of separate anions, giving one-dimensional chain structures extending across the (111) plane (Fig. 2).

Experimental

A mixture of pyrazole (0.68 g, 10 mmol) and oxalic acid (0.95 g, 10 mmol) in water was stirred for several days at ambient temperature. Colourless crystal plates of the title compound suitable for X-ray analysis were obtained.

Refinement

Hydrogen atom positions were calculated and allowed to ride on their parent atoms with aromatic C—H = 0.93 Å, N—H = 0.86 Å and O—H = 0.82 Å, and with U_iso(H) = 1.2U_eq(C or N) and U_iso(H) = 1.5U_eq(O).

Figures

Fig. 1.

The molecular structure and atom-numbering scheme for the title compound, with the displacement ellipsoids drawn at the 30% probability level.

Fig. 2.

The packing of the title compound in the unit cell viewed down the a axis. Hydrogen bonds are shown as dashed lines.

Crystal data

C3H5N2+·C2HO4−	Z = 2
Mr = 158.12	F(000) = 164
Triclinic, P1	Dx = 1.563 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 3.7286 (7) Å	Cell parameters from 1527 reflections
b = 9.836 (2) Å	θ = 2.4–27.5°
c = 10.487 (2) Å	µ = 0.14 mm−1
α = 117.35 (3)°	T = 293 K
β = 97.01 (3)°	Sheet, colourless
γ = 93.65 (3)°	0.26 × 0.22 × 0.14 mm
V = 335.92 (14) Å3

Data collection

Rigaku SCXmini CCD diffractometer	1527 independent reflections
Radiation source: fine-focus sealed tube	702 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.063
CCD_Profile_fitting scans	θmax = 27.5°, θmin = 3.9°
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	h = −4→4
Tmin = 0.965, Tmax = 0.993	k = −12→12
3484 measured reflections	l = −13→13

Refinement

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)] = 0.095	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.285	H-atom parameters constrained
S = 1.07	w = 1/[σ2(Fo2) + (0.1349P)2 + 0.0952P] where P = (Fo2 + 2Fc2)/3
1527 reflections	(Δ/σ)max < 0.001
101 parameters	Δρmax = 0.48 e Å−3
0 restraints	Δρmin = −0.29 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	1.0872 (11)	0.0136 (5)	0.3057 (4)	0.0416 (11)
H1A	1.1595	−0.0585	0.3230	0.050*
N2	1.1523 (11)	0.1643 (5)	0.3992 (4)	0.0412 (11)
H2A	1.2729	0.2054	0.4865	0.049*
C1	0.9992 (15)	0.2395 (6)	0.3352 (6)	0.0493 (15)
H1	1.0047	0.3461	0.3773	0.059*
C2	0.8307 (15)	0.1355 (7)	0.1967 (6)	0.0505 (15)
H2	0.7020	0.1567	0.1277	0.061*
C3	0.8931 (15)	−0.0076 (7)	0.1818 (6)	0.0477 (14)
H3	0.8131	−0.1021	0.0993	0.057*
O1	0.3997 (10)	0.8001 (4)	0.3600 (3)	0.0475 (10)
O2	0.6353 (11)	0.5351 (4)	0.3418 (4)	0.0577 (12)
O3	0.0807 (11)	0.6588 (4)	0.1355 (4)	0.0581 (11)
O4	0.3270 (11)	0.4012 (4)	0.1179 (4)	0.0554 (11)
H4	0.1905	0.4187	0.0612	0.083*
C4	0.2907 (14)	0.6762 (6)	0.2446 (5)	0.0402 (13)
C5	0.4374 (14)	0.5304 (6)	0.2400 (5)	0.0425 (13)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.049 (3)	0.033 (2)	0.041 (2)	0.0045 (19)	−0.0029 (19)	0.019 (2)
N2	0.048 (3)	0.034 (2)	0.031 (2)	0.005 (2)	−0.0023 (19)	0.0087 (19)
C1	0.053 (3)	0.045 (3)	0.056 (4)	0.011 (3)	0.006 (3)	0.029 (3)
C2	0.053 (4)	0.052 (4)	0.048 (3)	0.010 (3)	−0.002 (3)	0.027 (3)
C3	0.047 (3)	0.042 (3)	0.041 (3)	0.004 (2)	−0.006 (2)	0.011 (3)
O1	0.062 (2)	0.033 (2)	0.037 (2)	0.0087 (17)	−0.0074 (17)	0.0110 (18)
O2	0.076 (3)	0.043 (2)	0.045 (2)	0.0122 (19)	−0.0127 (19)	0.018 (2)
O3	0.077 (3)	0.042 (2)	0.044 (2)	0.0123 (19)	−0.0126 (19)	0.0155 (19)
O4	0.075 (3)	0.032 (2)	0.045 (2)	0.0098 (19)	−0.0082 (19)	0.0113 (19)
C4	0.047 (3)	0.032 (3)	0.035 (3)	0.005 (2)	0.005 (2)	0.011 (2)
C5	0.050 (3)	0.033 (3)	0.039 (3)	0.003 (2)	0.004 (3)	0.013 (3)

Geometric parameters (Å, º)

N1—C3	1.325 (6)	C2—H2	0.9300
N1—N2	1.333 (5)	C3—H3	0.9300
N1—H1A	0.8601	O1—C4	1.256 (6)
N2—C1	1.319 (6)	O2—C5	1.202 (6)
N2—H2A	0.8600	O3—C4	1.239 (6)
C1—C2	1.372 (7)	O4—C5	1.317 (6)
C1—H1	0.9300	O4—H4	0.8200
C2—C3	1.380 (8)	C4—C5	1.549 (7)
C3—N1—N2	109.3 (4)	C3—C2—H2	127.4
C3—N1—H1A	125.3	N1—C3—C2	108.0 (5)
N2—N1—H1A	125.4	N1—C3—H3	126.0
C1—N2—N1	108.4 (4)	C2—C3—H3	126.0
C1—N2—H2A	125.8	C5—O4—H4	109.5
N1—N2—H2A	125.8	O3—C4—O1	127.0 (5)
N2—C1—C2	109.1 (5)	O3—C4—C5	117.3 (4)
N2—C1—H1	125.4	O1—C4—C5	115.7 (4)
C2—C1—H1	125.4	O2—C5—O4	122.4 (5)
C1—C2—C3	105.2 (5)	O2—C5—C4	122.1 (5)
C1—C2—H2	127.4	O4—C5—C4	115.4 (4)
C3—N1—N2—C1	0.1 (6)	O3—C4—C5—O2	−178.2 (5)
N1—N2—C1—C2	0.0 (6)	O1—C4—C5—O2	1.9 (8)
N2—C1—C2—C3	0.0 (6)	O3—C4—C5—O4	1.0 (7)
N2—N1—C3—C2	−0.1 (6)	O1—C4—C5—O4	−178.9 (4)
C1—C2—C3—N1	0.1 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1i	0.86	1.86	2.709 (5)	170
N2—H2A···O1ii	0.86	1.92	2.715 (5)	153
O4—H4···O3iii	0.82	1.95	2.679 (5)	147

Symmetry codes: (i) x+1, y−1, z; (ii) −x+2, −y+1, −z+1; (iii) −x, −y+1, −z.