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

In the title compound, C(6)H(10)N(2)O, the 2,3-dihydro-1H-pyrazole ring is approximately planar, with a maximum deviation of 0.013 (1) Å. Pairs of inter-molecular N-H⋯O hydrogen bonds link neighboring mol-ecules into dimers, generating R(2) (2)(8) ring motifs. These dimers are further linked into two-dimensional arrays parallel to the bc plane by inter-molecular N-H⋯O hydrogen bonds. The crystal structure is further stabilized by C-H⋯π inter-actions.

Related literature

For the background to and the biological activity of 3-ethyl-4-methyl-1H-pyrazol-5-ol, see: Brogden (1986 ▶); Coersmeier et al. (1986); Gursoy et al. (2000 ▶); Ragavan et al. (2009 ▶, 2010 ▶); Watanabe et al. (1984 ▶); Kawai et al. (1997 ▶); Wu et al. (2002 ▶). For related structures, see: Shahani et al. (2009 ▶, 2010 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For reference bond-length data, see: Allen et al. (1987 ▶). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C6H10N2O

M = 126.16

Monoclinic,

a = 8.374 (2) Å

b = 7.2881 (16) Å

c = 11.300 (3) Å

β = 109.955 (5)°

V = 648.3 (3) Å3

Z = 4

Mo Kα radiation

μ = 0.09 mm−1

T = 100 K

0.52 × 0.16 × 0.09 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T min = 0.954, T max = 0.992

10018 measured reflections

2745 independent reflections

2325 reflections with I > 2σ(I)

R int = 0.029

Refinement

R[F 2 > 2σ(F 2)] = 0.039

wR(F 2) = 0.123

S = 1.14

2745 reflections

122 parameters

All H-atom parameters refined

Δρmax = 0.52 e Å−3

Δρmin = −0.35 e Å−3

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053681001696X/wn2385sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053681001696X/wn2385Isup2.hkl

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

C6H10N2O	F(000) = 272
Mr = 126.16	Dx = 1.293 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3666 reflections
a = 8.374 (2) Å	θ = 2.6–34.5°
b = 7.2881 (16) Å	µ = 0.09 mm−1
c = 11.300 (3) Å	T = 100 K
β = 109.955 (5)°	Plate, colourless
V = 648.3 (3) Å3	0.52 × 0.16 × 0.09 mm
Z = 4

Bruker APEXII DUO CCD area-detector diffractometer	2745 independent reflections
Radiation source: fine-focus sealed tube	2325 reflections with I > 2σ(I)
graphite	Rint = 0.029
φ and ω scans	θmax = 34.6°, θmin = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −13→13
Tmin = 0.954, Tmax = 0.992	k = −11→11
10018 measured reflections	l = −18→17

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.123	All H-atom parameters refined
S = 1.14	w = 1/[σ2(Fo2) + (0.0715P)2 + 0.0472P] where P = (Fo2 + 2Fc2)/3
2745 reflections	(Δ/σ)max < 0.001
122 parameters	Δρmax = 0.52 e Å−3
0 restraints	Δρmin = −0.35 e Å−3

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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. 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.

	x	y	z	Uiso*/Ueq
O1	0.42822 (7)	0.62337 (8)	0.11992 (5)	0.01463 (13)
N1	0.42529 (8)	0.69441 (9)	−0.08076 (6)	0.01353 (13)
N2	0.35794 (9)	0.82809 (9)	−0.16813 (6)	0.01431 (13)
C1	0.38533 (9)	0.73007 (10)	0.02374 (6)	0.01110 (13)
C2	0.29351 (9)	0.89787 (9)	0.00188 (6)	0.01142 (13)
C3	0.28136 (9)	0.95309 (10)	−0.11791 (7)	0.01249 (14)
C4	0.19811 (10)	1.11714 (10)	−0.19250 (7)	0.01638 (15)
C5	0.05452 (11)	1.06785 (12)	−0.31308 (8)	0.02089 (17)
C6	0.22769 (10)	0.99011 (11)	0.09370 (7)	0.01700 (15)
H4A	0.1538 (18)	1.1950 (18)	−0.1386 (13)	0.026 (3)*
H4B	0.2822 (16)	1.1904 (17)	−0.2159 (11)	0.019 (3)*
H5A	−0.0064 (17)	1.1779 (18)	−0.3632 (13)	0.025 (3)*
H5B	−0.0336 (19)	0.991 (2)	−0.2946 (14)	0.038 (4)*
H5C	0.0961 (19)	0.994 (2)	−0.3704 (15)	0.036 (4)*
H6A	0.3195 (17)	1.0187 (18)	0.1773 (13)	0.027 (3)*
H6B	0.147 (2)	0.9115 (19)	0.1185 (14)	0.033 (4)*
H6C	0.163 (2)	1.103 (2)	0.0557 (16)	0.044 (4)*
H1N1	0.4808 (19)	0.5936 (19)	−0.0921 (14)	0.028 (3)*
H1N2	0.3762 (17)	0.8332 (19)	−0.2486 (13)	0.028 (3)*

	U11	U22	U33	U12	U13	U23
O1	0.0221 (3)	0.0147 (2)	0.0089 (2)	0.00498 (18)	0.00754 (19)	0.00296 (17)
N1	0.0211 (3)	0.0125 (3)	0.0092 (2)	0.0048 (2)	0.0080 (2)	0.00233 (19)
N2	0.0221 (3)	0.0130 (3)	0.0098 (3)	0.0033 (2)	0.0080 (2)	0.0027 (2)
C1	0.0144 (3)	0.0120 (3)	0.0078 (3)	0.0006 (2)	0.0050 (2)	−0.0002 (2)
C2	0.0142 (3)	0.0109 (3)	0.0096 (3)	0.0009 (2)	0.0047 (2)	−0.0003 (2)
C3	0.0159 (3)	0.0106 (3)	0.0110 (3)	0.0000 (2)	0.0047 (2)	0.0000 (2)
C4	0.0213 (3)	0.0118 (3)	0.0143 (3)	0.0012 (2)	0.0039 (3)	0.0027 (2)
C5	0.0212 (3)	0.0193 (3)	0.0178 (3)	0.0024 (3)	0.0010 (3)	0.0032 (3)
C6	0.0208 (3)	0.0187 (3)	0.0132 (3)	0.0048 (3)	0.0079 (3)	−0.0015 (3)

O1—C1	1.2839 (9)	C4—C5	1.5209 (12)
N1—C1	1.3578 (9)	C4—H4A	0.993 (14)
N1—N2	1.3645 (9)	C4—H4B	0.989 (13)
N1—H1N1	0.902 (14)	C5—H5A	1.013 (13)
N2—C3	1.3459 (10)	C5—H5B	1.003 (15)
N2—H1N2	0.972 (14)	C5—H5C	0.992 (16)
C1—C2	1.4206 (10)	C6—H6A	1.015 (13)
C2—C3	1.3823 (10)	C6—H6B	0.994 (15)
C2—C6	1.4908 (10)	C6—H6C	1.000 (16)
C3—C4	1.4916 (11)
C1—N1—N2	109.19 (6)	C5—C4—H4A	109.8 (8)
C1—N1—H1N1	124.9 (9)	C3—C4—H4B	110.2 (7)
N2—N1—H1N1	125.8 (9)	C5—C4—H4B	107.8 (7)
C3—N2—N1	108.49 (6)	H4A—C4—H4B	107.7 (11)
C3—N2—H1N2	128.1 (8)	C4—C5—H5A	114.0 (8)
N1—N2—H1N2	123.1 (8)	C4—C5—H5B	111.0 (9)
O1—C1—N1	122.64 (7)	H5A—C5—H5B	106.9 (12)
O1—C1—C2	130.32 (6)	C4—C5—H5C	111.5 (9)
N1—C1—C2	107.04 (6)	H5A—C5—H5C	106.6 (12)
C3—C2—C1	105.99 (6)	H5B—C5—H5C	106.3 (12)
C3—C2—C6	128.98 (7)	C2—C6—H6A	113.4 (8)
C1—C2—C6	125.03 (6)	C2—C6—H6B	112.5 (9)
N2—C3—C2	109.23 (6)	H6A—C6—H6B	103.1 (11)
N2—C3—C4	120.16 (7)	C2—C6—H6C	110.4 (10)
C2—C3—C4	130.59 (7)	H6A—C6—H6C	110.9 (12)
C3—C4—C5	113.02 (7)	H6B—C6—H6C	106.1 (13)
C3—C4—H4A	108.2 (8)
C1—N1—N2—C3	2.59 (8)	N1—N2—C3—C4	179.19 (6)
N2—N1—C1—O1	177.88 (7)	C1—C2—C3—N2	0.73 (8)
N2—N1—C1—C2	−2.09 (8)	C6—C2—C3—N2	−179.69 (7)
O1—C1—C2—C3	−179.13 (7)	C1—C2—C3—C4	179.34 (7)
N1—C1—C2—C3	0.84 (8)	C6—C2—C3—C4	−1.08 (13)
O1—C1—C2—C6	1.27 (12)	N2—C3—C4—C5	60.72 (10)
N1—C1—C2—C6	−178.76 (7)	C2—C3—C4—C5	−117.76 (9)
N1—N2—C3—C2	−2.03 (8)

Cg1 is the centroid of the 1H-pyrazole ring (C1–C3/N1/N2).

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O1i	0.902 (15)	1.829 (15)	2.7267 (11)	174.0 (16)
N2—H1N2···O1ii	0.972 (14)	1.715 (14)	2.6777 (10)	169.9 (13)
C5—H5A···Cg1iii	1.013 (13)	2.896 (15)	3.6749 (14)	134.2 (11)

Table 1

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the 1H-pyrazole ring (C1–C3/N1/N2).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N1⋯O1i	0.902 (15)	1.829 (15)	2.7267 (11)	174.0 (16)
N2—H1N2⋯O1ii	0.972 (14)	1.715 (14)	2.6777 (10)	169.9 (13)
C5—H5A⋯Cg1iii	1.013 (13)	2.896 (15)	3.6749 (14)	134.2 (11)

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