2-(4-Chloro­phen­yl)-5-methyl-1H-pyrazol-3(2H)-one

In the title compound, C₁₀H₉ClN₂O, the benzene ring is twisted with respect to the pyrazole plane, with a dihedral angle of 15.81 (11)°. The centroid-to-centroid separation of 3.721 (4) Å indicates π–π stacking between parallel benzene rings.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.038
• wR factor = 0.111
• Data-to-parameter ratio = 12.6

checkCIF/PLATON results

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Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

2-(4-Chlorophenyl)-5-methyl-1H-pyrazol-3(2H)-one

Crystal data

C10H9ClN2O	Z = 2
Mr = 208.64	F(000) = 216
Triclinic, P1	Dx = 1.439 Mg m^−3
Hall symbol: -P 1	Melting point: 441 K
a = 5.885 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.704 (7) Å	Cell parameters from 1622 reflections
c = 11.38 (1) Å	θ = 2.8–26.5°
α = 105.980 (13)°	µ = 0.36 mm^−1
β = 94.719 (14)°	T = 294 K
γ = 101.250 (13)°	Block, colourless
V = 481.4 (7) Å^3	0.30 × 0.26 × 0.22 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1669 independent reflections
Radiation source: fine-focus sealed tube	1421 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
φ and ω scans	θmax = 25.0°, θmin = 1.9°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −5→6
Tmin = 0.899, Tmax = 0.925	k = −9→9
2397 measured reflections	l = −13→10

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.111	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.054P)^2 + 0.1893P] where P = (Fo^2 + 2Fc^2)/3
1669 reflections	(Δ/σ)max = 0.003
132 parameters	Δρmax = 0.21 e Å^−3
0 restraints	Δρmin = −0.26 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
Cl1	0.46931 (12)	−0.04642 (9)	0.14776 (5)	0.0653 (3)
O1	0.1306 (2)	0.3563 (2)	0.70412 (13)	0.0514 (4)
N1	0.5211 (2)	0.3831 (2)	0.67330 (13)	0.0340 (4)
N2	0.7367 (3)	0.4918 (2)	0.73944 (15)	0.0397 (4)
C1	0.5052 (3)	0.2847 (2)	0.54670 (16)	0.0324 (4)
C2	0.6975 (3)	0.3122 (3)	0.48463 (18)	0.0414 (5)
H2	0.8339	0.3990	0.5253	0.050*
C3	0.6851 (4)	0.2103 (3)	0.36256 (18)	0.0457 (5)
H3	0.8139	0.2273	0.3214	0.055*
C4	0.4813 (4)	0.0834 (3)	0.30197 (17)	0.0416 (5)
C5	0.2884 (4)	0.0560 (3)	0.36099 (19)	0.0470 (5)
H5	0.1514	−0.0288	0.3188	0.056*
C6	0.2997 (3)	0.1562 (3)	0.48417 (19)	0.0423 (5)
H6	0.1705	0.1377	0.5249	0.051*
C7	0.3443 (3)	0.4248 (3)	0.74289 (17)	0.0362 (4)
C8	0.4626 (3)	0.5550 (3)	0.85669 (17)	0.0418 (5)
H8	0.3916	0.6082	0.9233	0.050*
C9	0.6962 (3)	0.5883 (3)	0.85163 (17)	0.0400 (5)
C10	0.8974 (4)	0.7108 (3)	0.9465 (2)	0.0594 (6)
H10A	0.9931	0.6359	0.9716	0.089*
H10B	0.8384	0.7786	1.0169	0.089*
H10C	0.9895	0.7961	0.9117	0.089*
H2A	0.857 (4)	0.450 (3)	0.730 (2)	0.058 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0860 (5)	0.0646 (4)	0.0351 (3)	0.0180 (3)	0.0105 (3)	−0.0028 (3)
O1	0.0266 (8)	0.0645 (10)	0.0507 (9)	0.0087 (6)	0.0096 (6)	−0.0027 (7)
N1	0.0236 (8)	0.0403 (8)	0.0329 (8)	0.0058 (6)	0.0050 (6)	0.0034 (7)
N2	0.0267 (9)	0.0469 (9)	0.0382 (9)	0.0085 (7)	0.0051 (7)	0.0005 (7)
C1	0.0320 (10)	0.0351 (9)	0.0309 (9)	0.0114 (7)	0.0062 (7)	0.0080 (7)
C2	0.0341 (10)	0.0503 (11)	0.0354 (10)	0.0018 (8)	0.0079 (8)	0.0102 (9)
C3	0.0446 (12)	0.0589 (13)	0.0343 (10)	0.0094 (10)	0.0143 (9)	0.0140 (9)
C4	0.0518 (12)	0.0409 (10)	0.0311 (10)	0.0150 (9)	0.0052 (8)	0.0063 (8)
C5	0.0426 (12)	0.0437 (11)	0.0431 (11)	0.0037 (9)	0.0004 (9)	0.0002 (9)
C6	0.0326 (10)	0.0441 (11)	0.0431 (11)	0.0053 (8)	0.0090 (8)	0.0030 (9)
C7	0.0287 (10)	0.0431 (10)	0.0367 (10)	0.0115 (8)	0.0095 (7)	0.0081 (8)
C8	0.0361 (10)	0.0502 (11)	0.0350 (10)	0.0143 (9)	0.0098 (8)	0.0014 (8)
C9	0.0376 (11)	0.0431 (11)	0.0351 (10)	0.0124 (8)	0.0049 (8)	0.0025 (8)
C10	0.0396 (12)	0.0672 (15)	0.0509 (13)	0.0088 (10)	−0.0002 (9)	−0.0110 (11)

Geometric parameters (Å, º)

Cl1—C4	1.753 (2)	C3—H3	0.9300
O1—C7	1.256 (2)	C4—C5	1.377 (3)
N1—N2	1.400 (2)	C5—C6	1.391 (3)
N1—C1	1.417 (2)	C5—H5	0.9300
N1—C7	1.392 (2)	C6—H6	0.9300
N2—C9	1.355 (3)	C7—C8	1.426 (3)
N2—H2A	0.84 (3)	C8—C9	1.357 (3)
C1—C2	1.394 (3)	C8—H8	0.9300
C1—C6	1.397 (3)	C9—C10	1.500 (3)
C2—C3	1.383 (3)	C10—H10A	0.9600
C2—H2	0.9300	C10—H10B	0.9600
C3—C4	1.380 (3)	C10—H10C	0.9600
C7—N1—N2	108.91 (15)	C6—C5—H5	120.2
C7—N1—C1	129.69 (15)	C5—C6—C1	119.97 (18)
N2—N1—C1	119.94 (15)	C5—C6—H6	120.0
C9—N2—N1	107.48 (16)	C1—C6—H6	120.0
C9—N2—H2A	122.4 (17)	O1—C7—N1	123.28 (17)
N1—N2—H2A	119.3 (17)	O1—C7—C8	131.64 (17)
C2—C1—C6	119.58 (18)	N1—C7—C8	105.07 (16)
C2—C1—N1	120.00 (16)	C9—C8—C7	108.60 (17)
C6—C1—N1	120.40 (16)	C9—C8—H8	125.7
C3—C2—C1	119.96 (18)	C7—C8—H8	125.7
C3—C2—H2	120.0	N2—C9—C8	109.75 (17)
C1—C2—H2	120.0	N2—C9—C10	119.95 (19)
C4—C3—C2	119.89 (18)	C8—C9—C10	130.30 (19)
C4—C3—H3	120.1	C9—C10—H10A	109.5
C2—C3—H3	120.1	C9—C10—H10B	109.5
C5—C4—C3	121.09 (18)	H10A—C10—H10B	109.5
C5—C4—Cl1	119.55 (16)	C9—C10—H10C	109.5
C3—C4—Cl1	119.36 (16)	H10A—C10—H10C	109.5
C4—C5—C6	119.51 (19)	H10B—C10—H10C	109.5
C4—C5—H5	120.2
C7—N1—N2—C9	4.5 (2)	C4—C5—C6—C1	0.6 (3)
C1—N1—N2—C9	172.07 (16)	C2—C1—C6—C5	0.4 (3)
C7—N1—C1—C2	157.37 (19)	N1—C1—C6—C5	−177.99 (17)
N2—N1—C1—C2	−7.2 (3)	N2—N1—C7—O1	175.83 (18)
C7—N1—C1—C6	−24.3 (3)	C1—N1—C7—O1	9.9 (3)
N2—N1—C1—C6	171.14 (17)	N2—N1—C7—C8	−3.3 (2)
C6—C1—C2—C3	−1.1 (3)	C1—N1—C7—C8	−169.20 (17)
N1—C1—C2—C3	177.26 (17)	O1—C7—C8—C9	−178.1 (2)
C1—C2—C3—C4	0.9 (3)	N1—C7—C8—C9	0.9 (2)
C2—C3—C4—C5	0.1 (3)	N1—N2—C9—C8	−4.0 (2)
C2—C3—C4—Cl1	−179.35 (16)	N1—N2—C9—C10	176.84 (19)
C3—C4—C5—C6	−0.8 (3)	C7—C8—C9—N2	2.0 (2)
Cl1—C4—C5—C6	178.61 (15)	C7—C8—C9—C10	−179.0 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O1^i	0.84 (3)	1.90 (3)	2.737 (3)	179 (2)

Symmetry code: (i) x+1, y, z.