3-Phenyl-1H-pyrazole-5-carboxylic acid

In the title compound, C₁₀H₈N₂O₂, the dihedral angle between the phenyl and pyrazole ring planes is 21.27 (6)°. Inter­molecular O—H...O and N—H...N hydrogen bonds link the mol­ecules into chains along c. These are further connected by inter­molecular C—H...O hydrogen bonds, resulting in a two-dimensional framework.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.054
• wR factor = 0.167
• Data-to-parameter ratio = 13.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H7     ..  O2      ..       2.70 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Pyrazole carboxylic acid and ester derivatives exhibit useful pharmaceutical properties, for example as agonists for the nicotinic acid receptor, refered to as RUP25 herein (Shin et al., 2005).

The molecular structure of (I) is shown in Fig. 1. The dihedral angle between the phenyl plane and the pyrazole plane is 21.27 (6) Å. The carboxylate C4—O1—O2 plane, is twisted slightly with respect to the pyrazole ring plane, the dihedral angle between them is 9.0 (1) °.

In the crystal structure, intermolecular O1—H1···O2ⁱ [symmetry code: (i) 1 - x, 2 - y, 1 - z] and N2—H2···N1ⁱⁱ [symmetry code: (ii) 1 - x, y - 1/2, -z + 3/2] hydrogen bonds link the molecules into chains, which are further connected by intermolecular C7—H7···O2ⁱⁱⁱ [symmetry code: (iii) -x, y + 3/2, -z + 3/2] hydrogen bonds (C—O =3.531 (3) Å), resulting in a two-dimensional-dimensional framework.

Related literature

For information on the pharmaceutical properties of the title compound, see: Shin et al. (2005).

S2. Experimental

To a stirred solution of NaOH (300 ml, 20%) at 350 K was added 5- phenyl-2H-pyrazole-3-carboxylic acid ethyl ester (21.6 g, 0.1 mol), and the solution was stirred for 8 h. The reaction mixture was cooled to 293 K, filtered. A white flocculent precipitate appeared when the filtrate was adjusted to pH = 3–5 using dilute HCl. The title compound (yield 16.90 g, 89.90%) was obtained by filtering this precipitate and crystals appropriate for data collection were obtained by recrystallization from acetone/methanol (1:1).

S3. Refinement

All H atoms bound to C were included in calculated positions and refined as riding with C—H= 0.93 Å, and U_iso(H)= 1.2 U_eq(C). Other hydrogen atoms were located in a difference Fourier map and refined freely with U_iso(H) = 1.5 U_eq(O) and U_iso(H) = 1.2 U_eq(N) respectively.

Computing details

Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Berndt, 2005); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2005).

Figures

	Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids.
	Fig. 2. The crystal packing of (I), view down the b axis, showing the one dimensional chain structure extending along the c axis. Hydrogen bonds are shown as dashed lines.
	Fig. 3. The crystal packing of (I), viewed down the b axis, showing the two-dimensional-dimensional hydrogen-bonded framework. Hydrogen bonds are shown as dashed lines.

3-Phenyl-1H-pyrazole-5-carboxylic acid

Crystal data

C10H8N2O2	F(000) = 392
Mr = 188.18	Dx = 1.350 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: -P 2ybc	Cell parameters from 1971 reflections
a = 10.2391 (12) Å	θ = 2.7–25.0°
b = 5.3647 (6) Å	µ = 0.10 mm^−1
c = 17.5907 (17) Å	T = 291 K
β = 106.581 (8)°	Block, colorless
V = 926.07 (17) Å^3	0.32 × 0.30 × 0.18 mm
Z = 4

Data collection

Rigaku Saturn diffractometer	1817 independent reflections
Radiation source: rotating anode	1377 reflections with I > 2σ(I)
Confocal monochromator	Rint = 0.046
Detector resolution: 7.31 pixels mm^-1	θmax = 26.0°, θmin = 2.1°
ω scans	h = −12→12
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2005)	k = −6→6
Tmin = 0.970, Tmax = 0.983	l = −21→21
9603 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.167	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.1024P)^2] where P = (Fo^2 + 2Fc^2)/3
1817 reflections	(Δ/σ)max < 0.001
135 parameters	Δρmax = 0.19 e Å^−3
1 restraint	Δρmin = −0.16 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
O1	0.54576 (15)	0.8690 (3)	0.59886 (8)	0.0705 (5)
H1	0.571 (2)	0.983 (4)	0.5702 (13)	0.106*
O2	0.38316 (15)	0.7806 (3)	0.48748 (7)	0.0705 (5)
N1	0.45958 (15)	0.4857 (3)	0.67529 (8)	0.0535 (5)
N2	0.38121 (16)	0.3093 (3)	0.69483 (9)	0.0529 (5)
H2	0.4141 (19)	0.226 (4)	0.7415 (12)	0.063*
C1	0.39024 (17)	0.5507 (3)	0.60188 (9)	0.0486 (5)
C2	0.26909 (17)	0.4153 (3)	0.57510 (10)	0.0510 (5)
H2A	0.2045	0.4275	0.5259	0.061*
C3	0.26539 (18)	0.2603 (3)	0.63673 (10)	0.0476 (5)
C4	0.44173 (19)	0.7448 (3)	0.55878 (11)	0.0526 (5)
C5	0.16279 (18)	0.0802 (3)	0.64533 (10)	0.0494 (5)
C6	0.0304 (2)	0.0999 (4)	0.59687 (12)	0.0617 (6)
H6	0.0071	0.2280	0.5599	0.074*
C7	−0.0674 (2)	−0.0702 (5)	0.60325 (14)	0.0744 (7)
H7	−0.1560	−0.0552	0.5704	0.089*
C8	−0.0356 (3)	−0.2601 (4)	0.65715 (15)	0.0775 (7)
H8	−0.1018	−0.3747	0.6607	0.093*
C9	0.0940 (3)	−0.2798 (4)	0.70570 (14)	0.0748 (7)
H9	0.1157	−0.4083	0.7427	0.090*
C10	0.1939 (2)	−0.1121 (3)	0.70098 (12)	0.0606 (6)
H10	0.2818	−0.1275	0.7349	0.073*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0759 (10)	0.0725 (10)	0.0537 (9)	−0.0270 (7)	0.0033 (7)	0.0068 (7)
O2	0.0755 (10)	0.0812 (10)	0.0451 (8)	−0.0211 (8)	0.0018 (7)	0.0123 (7)
N1	0.0577 (9)	0.0554 (9)	0.0418 (9)	−0.0068 (7)	0.0053 (7)	0.0030 (7)
N2	0.0602 (10)	0.0535 (9)	0.0394 (9)	−0.0042 (7)	0.0053 (7)	0.0062 (7)
C1	0.0568 (11)	0.0479 (10)	0.0386 (9)	−0.0023 (8)	0.0096 (8)	0.0000 (7)
C2	0.0549 (11)	0.0528 (10)	0.0381 (10)	−0.0035 (8)	0.0016 (8)	0.0014 (7)
C3	0.0552 (11)	0.0441 (10)	0.0402 (9)	0.0009 (7)	0.0083 (8)	0.0003 (7)
C4	0.0560 (11)	0.0533 (11)	0.0448 (11)	−0.0049 (8)	0.0083 (9)	−0.0010 (8)
C5	0.0588 (11)	0.0454 (10)	0.0461 (10)	−0.0029 (8)	0.0181 (9)	−0.0055 (8)
C6	0.0646 (12)	0.0622 (12)	0.0561 (12)	−0.0084 (9)	0.0136 (10)	−0.0043 (9)
C7	0.0669 (14)	0.0816 (16)	0.0772 (16)	−0.0174 (11)	0.0244 (11)	−0.0203 (12)
C8	0.0873 (17)	0.0698 (15)	0.0907 (18)	−0.0229 (13)	0.0502 (15)	−0.0199 (13)
C9	0.106 (2)	0.0524 (12)	0.0796 (16)	−0.0020 (12)	0.0487 (16)	0.0045 (11)
C10	0.0739 (13)	0.0519 (11)	0.0594 (13)	0.0036 (9)	0.0246 (10)	0.0050 (9)

Geometric parameters (Å, º)

O1—C4	1.283 (2)	C5—C6	1.384 (3)
O1—H1	0.876 (10)	C5—C10	1.395 (3)
O2—C4	1.241 (2)	C6—C7	1.383 (3)
N1—C1	1.330 (2)	C6—H6	0.9300
N1—N2	1.347 (2)	C7—C8	1.366 (3)
N2—C3	1.352 (2)	C7—H7	0.9300
N2—H2	0.91 (2)	C8—C9	1.362 (3)
C1—C2	1.398 (2)	C8—H8	0.9300
C1—C4	1.472 (3)	C9—C10	1.382 (3)
C2—C3	1.375 (2)	C9—H9	0.9300
C2—H2A	0.9300	C10—H10	0.9300
C3—C5	1.467 (2)
C4—O1—H1	112.4 (16)	C6—C5—C3	119.40 (16)
C1—N1—N2	103.88 (14)	C10—C5—C3	122.18 (17)
N1—N2—C3	113.67 (14)	C7—C6—C5	120.3 (2)
N1—N2—H2	118.8 (12)	C7—C6—H6	119.9
C3—N2—H2	127.2 (13)	C5—C6—H6	119.9
N1—C1—C2	111.56 (16)	C8—C7—C6	120.9 (2)
N1—C1—C4	121.00 (16)	C8—C7—H7	119.5
C2—C1—C4	127.44 (15)	C6—C7—H7	119.5
C3—C2—C1	105.65 (15)	C9—C8—C7	119.3 (2)
C3—C2—H2A	127.2	C9—C8—H8	120.4
C1—C2—H2A	127.2	C7—C8—H8	120.4
N2—C3—C2	105.24 (15)	C8—C9—C10	121.2 (2)
N2—C3—C5	123.34 (15)	C8—C9—H9	119.4
C2—C3—C5	131.40 (17)	C10—C9—H9	119.4
O2—C4—O1	124.12 (18)	C9—C10—C5	119.9 (2)
O2—C4—C1	119.29 (16)	C9—C10—H10	120.0
O1—C4—C1	116.59 (16)	C5—C10—H10	120.0
C6—C5—C10	118.42 (17)
C1—N1—N2—C3	0.0 (2)	N2—C3—C5—C6	157.93 (18)
N2—N1—C1—C2	−0.3 (2)	C2—C3—C5—C6	−20.1 (3)
N2—N1—C1—C4	179.23 (16)	N2—C3—C5—C10	−22.1 (3)
N1—C1—C2—C3	0.4 (2)	C2—C3—C5—C10	159.78 (19)
C4—C1—C2—C3	−179.07 (18)	C10—C5—C6—C7	−0.9 (3)
N1—N2—C3—C2	0.2 (2)	C3—C5—C6—C7	179.05 (18)
N1—N2—C3—C5	−178.32 (16)	C5—C6—C7—C8	0.0 (3)
C1—C2—C3—N2	−0.33 (19)	C6—C7—C8—C9	0.7 (3)
C1—C2—C3—C5	178.01 (17)	C7—C8—C9—C10	−0.4 (3)
N1—C1—C4—O2	171.64 (19)	C8—C9—C10—C5	−0.5 (3)
C2—C1—C4—O2	−9.0 (3)	C6—C5—C10—C9	1.1 (3)
N1—C1—C4—O1	−8.9 (3)	C3—C5—C10—C9	−178.80 (18)
C2—C1—C4—O1	170.48 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···N1^i	0.91 (2)	2.10 (2)	2.961 (2)	158.0 (17)
O1—H1···O2^ii	0.88 (1)	1.77 (1)	2.6462 (19)	178 (2)
C7—H7···O2^iii	0.93	2.70	3.531 (3)	150

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