3-Ethyl-4-methyl-1H-pyrazol-2-ium-5-olate

Abstract

The title compound, C₆H₁₀N₂O, is a zwitterionic pyrazole derivative. The crystal packing is predominantly governed by a three-center iminium–amine N⁺—H⋯O⁻⋯H—N inter­action, leading to an undulating sheet-like structure lying parallel to (100).

Related literature

For related structures and the preparation of similar compounds, see: Ragavan et al. (2009 ▶, 2010 ▶) and references therein. For related salt-bridge-mediated sheet structures, see: Shylaja et al. (2008 ▶).

Experimental

Crystal data

• C₆H₁₀N₂O

• M _r = 126.16

• Monoclinic,

• a = 9.1299 (15) Å

• b = 7.1600 (11) Å

• c = 11.374 (2) Å

• β = 113.232 (9)°

• V = 683.2 (2) ų

• Z = 4

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 296 K

• 0.21 × 0.19 × 0.11 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.64, T _max = 0.83

• 12120 measured reflections

• 1332 independent reflections

• 961 reflections with I > 2σ(I)

• R _int = 0.034

Refinement

• R[F ² > 2σ(F ²)] = 0.049

• wR(F ²) = 0.136

• S = 1.03

• 1332 reflections

• 92 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT-Plus (Bruker, 2007 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Supplementary material file. DOI: 10.1107/S160053681102808X/su2287Isup3.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—H1⋯O5i	0.91 (2)	1.82 (2)	2.730 (2)	175 (2)
N2—H2⋯O5ii	0.96 (2)	1.75 (2)	2.693 (2)	168 (2)

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

As a part of our interest in antimicrobial compounds, we have synthesized the title pyrazole derivative using the procedure described earlier by (Ragavan et al., 2009, and references therein; 2010, and references therein).

The molecular structure of the title molecule is shown in Fig 1. The methyl atom (C3B) of the 3-ethyl substituent lies out of the mean plane of the pyrazole moiety (N1,N2,C3-C5) by 1.366 (4) Å.

The crystal packing is a fine balance of strong N—H···O hydrogen bonds (Table 1) and salt bridges, which normally tend to promote the formation of a planar structure and compact packing (Shylaja et al., 2008). In the title compound all the hydrogen bonding donors, iminium N⁺H (N1) and amine NH (N2), and the O^-(O1) acceptor, are in the plane of the pyrazole moiety, which would normally yield a planar hydrogen-bonded structure. However, in order to accommodate the out-of-plane methyl group, (C3B), an undulating hydrogen bonded sheet-like structure, lieing paralallel to (100), is formed (Fig. 2).

Experimental

The title compound was synthesized using the method described earlier by (Ragavan et al., 2009, 2010). It was crystallized using an ethanol-chloroform (1:1) mixture. Yield, 74%; m.p. 779-780 K.

Refinement

The NH atoms were located in a difference Fourier map and were freely refined: N2—H2 = 0.92 (2) Å and N1⁺—H1 = 0.95 (3) Å. The methylene and methyl hydrogen atoms were placed in calculated positions and refined as riding atoms: C-H = 0.97 and 0.96 Å, for CH and CH₃ H-atoms, respectively, with U_iso(H) = k × U_eq(C,) where k = 1.5 for CH₃ H-atoms and 1.2 for the CH H-atoms.

Figures

Fig. 1.

A view of the molecular structure of the title molecule, with labelling scheme and displacement ellipsoids drawn at the 30% probability level.

Fig. 2.

A view of the N—H···O hydrogen bonded (dashed cyan lines) sheet structure in the crystal structure of the title compound (see Table 1 for details).

Crystal data

C6H10N2O	F(000) = 272
Mr = 126.16	Dx = 1.227 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3015 reflections
a = 9.1299 (15) Å	θ = 2.4–22.9°
b = 7.1600 (11) Å	µ = 0.09 mm−1
c = 11.374 (2) Å	T = 296 K
β = 113.232 (9)°	Plate, colourless
V = 683.2 (2) Å3	0.21 × 0.19 × 0.11 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	1332 independent reflections
Radiation source: fine-focus sealed tube	961 reflections with I > 2σ(I)
graphite	Rint = 0.034
φ and ω scans	θmax = 26.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −11→11
Tmin = 0.64, Tmax = 0.83	k = −8→8
12120 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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.136	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ2(Fo2) + (0.0674P)2 + 0.2195P] where P = (Fo2 + 2Fc2)/3
1332 reflections	(Δ/σ)max < 0.001
92 parameters	Δρmax = 0.17 e Å−3
0 restraints	Δρmin = −0.21 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	0.0756 (2)	0.1929 (2)	0.58699 (14)	0.0427 (5)
H1	0.029 (3)	0.087 (3)	0.601 (2)	0.051 (6)*
N2	0.1373 (2)	0.3275 (2)	0.67795 (15)	0.0462 (5)
H2	0.116 (3)	0.326 (3)	0.754 (2)	0.062 (6)*
O5	0.07244 (17)	0.12652 (19)	0.38750 (11)	0.0489 (4)
C3	0.2107 (2)	0.4552 (3)	0.63369 (17)	0.0402 (5)
C3A	0.2903 (3)	0.6189 (3)	0.7141 (2)	0.0573 (6)
H3A1	0.2994	0.7177	0.6591	0.069*
H3A2	0.2238	0.6648	0.7566	0.069*
C3B	0.4512 (4)	0.5766 (4)	0.8123 (3)	0.1014 (12)
H3B1	0.4424	0.4859	0.8714	0.152*
H3B2	0.4982	0.6889	0.8577	0.152*
H3B3	0.5171	0.5277	0.7714	0.152*
C4	0.1999 (2)	0.4015 (2)	0.51474 (17)	0.0367 (5)
C4A	0.2643 (3)	0.4995 (3)	0.4291 (2)	0.0544 (6)
H41	0.3131	0.6149	0.4681	0.082*
H42	0.1789	0.5248	0.3482	0.082*
H43	0.3422	0.4216	0.4162	0.082*
C5	0.1135 (2)	0.2330 (3)	0.48611 (16)	0.0359 (5)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0661 (11)	0.0389 (9)	0.0308 (8)	−0.0145 (8)	0.0275 (8)	−0.0061 (7)
N2	0.0698 (12)	0.0444 (10)	0.0313 (9)	−0.0109 (8)	0.0275 (8)	−0.0098 (7)
O5	0.0759 (10)	0.0484 (8)	0.0304 (7)	−0.0197 (7)	0.0295 (7)	−0.0092 (6)
C3	0.0470 (11)	0.0362 (10)	0.0369 (10)	−0.0008 (8)	0.0162 (9)	−0.0008 (8)
C3A	0.0725 (15)	0.0467 (12)	0.0519 (13)	−0.0103 (11)	0.0237 (12)	−0.0149 (10)
C3B	0.084 (2)	0.082 (2)	0.097 (2)	−0.0121 (16)	−0.0077 (17)	−0.0341 (18)
C4	0.0428 (10)	0.0361 (10)	0.0322 (9)	−0.0018 (8)	0.0159 (8)	0.0016 (8)
C4A	0.0632 (14)	0.0566 (13)	0.0485 (12)	−0.0143 (11)	0.0274 (11)	0.0035 (10)
C5	0.0455 (10)	0.0378 (10)	0.0266 (9)	−0.0018 (8)	0.0165 (8)	0.0003 (8)

Geometric parameters (Å, °)

N1—C5	1.354 (2)	C3A—H3A2	0.9700
N1—N2	1.363 (2)	C3B—H3B1	0.9600
N1—H1	0.92 (2)	C3B—H3B2	0.9600
N2—C3	1.343 (3)	C3B—H3B3	0.9600
N2—H2	0.95 (3)	C4—C5	1.408 (3)
O5—C5	1.284 (2)	C4—C4A	1.495 (3)
C3—C4	1.372 (3)	C4A—H41	0.9600
C3—C3A	1.488 (3)	C4A—H42	0.9600
C3A—C3B	1.484 (4)	C4A—H43	0.9600
C3A—H3A1	0.9700
C5—N1—N2	109.01 (16)	H3B1—C3B—H3B2	109.5
C5—N1—H1	128.2 (13)	C3A—C3B—H3B3	109.5
N2—N1—H1	122.3 (13)	H3B1—C3B—H3B3	109.5
C3—N2—N1	108.38 (16)	H3B2—C3B—H3B3	109.5
C3—N2—H2	130.8 (14)	C3—C4—C5	106.50 (16)
N1—N2—H2	120.5 (14)	C3—C4—C4A	128.08 (17)
N2—C3—C4	109.04 (16)	C5—C4—C4A	125.42 (17)
N2—C3—C3A	120.03 (18)	C4—C4A—H41	109.5
C4—C3—C3A	130.90 (18)	C4—C4A—H42	109.5
C3B—C3A—C3	113.6 (2)	H41—C4A—H42	109.5
C3B—C3A—H3A1	108.8	C4—C4A—H43	109.5
C3—C3A—H3A1	108.8	H41—C4A—H43	109.5
C3B—C3A—H3A2	108.8	H42—C4A—H43	109.5
C3—C3A—H3A2	108.8	O5—C5—N1	122.03 (16)
H3A1—C3A—H3A2	107.7	O5—C5—C4	130.92 (17)
C3A—C3B—H3B1	109.5	N1—C5—C4	107.05 (15)
C3A—C3B—H3B2	109.5
C5—N1—N2—C3	1.6 (2)	C3A—C3—C4—C4A	−1.7 (3)
N1—N2—C3—C4	−1.4 (2)	N2—N1—C5—O5	178.68 (17)
N1—N2—C3—C3A	−179.69 (17)	N2—N1—C5—C4	−1.2 (2)
N2—C3—C3A—C3B	80.6 (3)	C3—C4—C5—O5	−179.5 (2)
C4—C3—C3A—C3B	−97.3 (3)	C4A—C4—C5—O5	0.9 (3)
N2—C3—C4—C5	0.7 (2)	C3—C4—C5—N1	0.3 (2)
C3A—C3—C4—C5	178.7 (2)	C4A—C4—C5—N1	−179.25 (18)
N2—C3—C4—C4A	−179.80 (19)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O5i	0.91 (2)	1.82 (2)	2.730 (2)	175 (2)
N2—H2···O5ii	0.96 (2)	1.75 (2)	2.693 (2)	168 (2)

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