5-tert-But­yl-4-nitro-1H-pyrazol-3-ol

Lynch, D.E.; McClenaghan, I.

doi:10.1107/S1600536805020544

organic compounds

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ISSN: 2056-9890

Volume 61| Part 8| August 2005| Pages o2347-o2348

https://doi.org/10.1107/S1600536805020544

5-tert-Butyl-4-nitro-1H-pyrazol-3-ol

Daniel E. Lynch ^a and Ian McClenaghan ^b ^*

^aSchool of Science and the Environment, Coventry University, Coventry CV1 5FB, England, and ^bKey Organics Ltd, Highfield Industrial Estate, Camelford, Cornwall PL32 9QZ, England
^*Correspondence e-mail: apx106@coventry.ac.uk

(Received 6 April 2005; accepted 28 June 2005; online 6 July 2005)

The structure of the title compound, C₇H₁₁N₃O₃, consists of molecules that pack in a linear hydrogen-bonded ribbon motif. This hydrogen-bonding arrangement is constructed through two dimer formations, one that is atypical of pyrazoles (N—H⋯N) and the other via an interaction from the hydroxy OH group to one of the nitro O atoms.

Comment

Pyrazoles and related compounds are common molecules used in coordination or organometallic chemistry as bridging ligands, utilizing the ring positions of the two N atoms. There are 1388 structures in the Cambridge Structural Database (CSD; Version 5.26, November 2004; Allen, 2002 ) that contain a pyrazole ring with the extra search constraints `no extra cyclic routes' and `require 3D coordinates'. This number reduces to 23 for 4-nitropyrazoles, 80 for 5-tert-butylpyrazoles, and 15 for 3-hydroxypyrazoles. Interestingly, there is only one structure (CSD refcode: WILBAU), that of 3,5-di-tert-butyl-4-nitropyrazole (Llamas-Saiz et al., 1994 ), which contains two of the three mentioned substituents.

In a series of studies on the preparation and hydrogen-bonding properties of 3,4,5-trisubstituted pyrazoles, we now report 5-tert-butyl-4-nitro-1H-pyrazol-3-ol, (I). The structure of (I) (Fig. 1) consists of molecules that pack to form a linear hydrogen-bonded ribbon motif (Fig. 2). The hydrogen-bonding arrangement can be described by two centrosymmetric dimer formations (Table 1). The first of these dimer formations is atypical of pyrazoles and involves an N1—H⋯N2 interaction, centred at ( $[{1\over 2}]$ ,0,0) described by an R₂²(6) graph set (Etter, 1990 ), while the second dimer formation, centred at (0,1,0), involves one intramolecular hydrogen-bonding association from O3—H to O42, forming an S(6) graph-set motif, and an R₂²(4) graph-set motif arising from the three-centre association involving H3 and two O42 atoms. The other O atom (O41) of the nitro group is not involved in the hydrogen-bond network. The ribbon motifs are stacked in the a-axis direction, the perpendicular distances between ribbon planes being 3.263 (2) and 3.195 (2) Å (calculated with PLATON; Spek, 2003 ).

Figure 1
The molecular configuration and atom-numbering scheme for (I)

. Displacement ellipsoids are drawn at the 50% probability level. H atoms are drawn as spheres of arbitrary radius.

Figure 2
A partial packing diagram for (I)

, showing the hydrogen-bonded (dashed lines) ribbon motif. For clarity, H atoms not involved in the hydrogen-bonding interactions have been omitted. [Symmetry codes: (i) −x + 1, −y, −z and (ii) −x, −y + 2, −z.]

Experimental

Synthetically, (I) originated from 3,5-di-tert-butylpyrazole, being produced by gently warming this compound in concentrated nitric acid. In this reaction, 3,5-di-tert-butylpyrazole is attacked by nitric acid to form the onium species, which then displaces one tert-butyl group. The subsequent vacant position is then filled by an OH group that does not tautomerize to form the pyrazolone. The title compound was obtained from Key Organics Ltd and crystals were grown from ethanol solution.

Crystal data

C₇H₁₁N₃O₃
M_r = 185.19
Triclinic, $[P \overline 1]$
a = 6.4870 (5) Å
b = 6.6560 (4) Å
c = 11.5588 (8) Å
α = 81.227 (4)°
β = 76.733 (3)°
γ = 65.037 (5)°
V = 439.50 (6) Å³
Z = 2
D_x = 1.399 Mg m⁻³
Mo Kα radiation
Cell parameters from 1899 reflections
θ = 2.9–27.5°
μ = 0.11 mm⁻¹
T = 120 (2) K
Plate, colourless
0.30 × 0.05 × 0.01 mm

Data collection

Bruker Nonius KappaCCD diffractometer
φ and ω scans
Absorption correction: multi-scan(SADABS; Sheldrick, 2003 )T_min = 0.968, T_max = 0.999
7496 measured reflections
1720 independent reflections
1494 reflections with I > 2σ(I)
R_int = 0.054
θ_max = 26.0°
h = −7 → 7
k = −7 → 8
l = −14 → 14

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.059
wR(F²) = 0.153
S = 1.19
1720 reflections
128 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F_o²) + (0.0798P)² + 0.125P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.47 e Å⁻³
Δρ_min = −0.43 e Å⁻³
Extinction correction: SHELXL97
Extinction coefficient: 0.28 (3)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯N2ⁱ	0.88 (3)	2.09 (3)	2.847 (2)	144 (2)
O3—H3⋯O42	0.87 (3)	2.02 (3)	2.718 (2)	136 (2)
O3—H3⋯O42ⁱⁱ	0.87 (3)	2.19 (3)	2.948 (2)	145 (2)
Symmetry codes: (i) -x+1, -y, -z; (ii) -x, -y+2, -z.

All tert-butyl H atoms were included in the refinement at calculated positions, in the riding-model approximation, with C—H distances of 0.98 Å. All H atoms involved in the hydrogen-bonding associations were located in Fourier syntheses and positional parameters were refined. The isotropic displacement parameters for all H atoms were set equal to 1.25U_eq of the carrier atom.

Data collection: COLLECT (Hooft, 1998 ); cell refinement: DENZO (Otwinowski & Minor, 1997 ) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536805020544/er6016sup1.cif

Structure factors: contains datablock (I). DOI: https://doi.org/10.1107/S1600536805020544/er6016Isup2.hkl

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

5-tert-butyl-4-nitro-1H-pyrazol-3-ol top

Crystal data top

C₇H₁₁N₃O₃	Z = 2
M_r = 185.19	F(000) = 196
Triclinic, P1	D_x = 1.399 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.4870 (5) Å	Cell parameters from 1899 reflections
b = 6.6560 (4) Å	θ = 2.9–27.5°
c = 11.5588 (8) Å	µ = 0.11 mm⁻¹
α = 81.227 (4)°	T = 120 K
β = 76.733 (3)°	Plate, colourless
γ = 65.037 (5)°	0.30 × 0.05 × 0.01 mm
V = 439.50 (6) Å³

Data collection top

Bruker Nonius 95 mm CCD camera on κ-goniostat diffractometer	1720 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	1494 reflections with I > 2σ(I)
10 cm confocal mirrors monochromator	R_int = 0.054
Detector resolution: 9.091 pixels mm^-1	θ_max = 26.0°, θ_min = 3.4°
φ and ω scans	h = −7→7
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	k = −7→8
T_min = 0.968, T_max = 0.999	l = −14→14
7496 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.059	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.153	w = 1/[σ²(F_o²) + (0.0798P)² + 0.125P] where P = (F_o² + 2F_c²)/3
S = 1.19	(Δ/σ)_max = 0.001
1720 reflections	Δρ_max = 0.47 e Å⁻³
128 parameters	Δρ_min = −0.43 e Å⁻³
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.28 (3)

Special details top

Experimental. The minimum and maximum absorption values stated above are those calculated in SHELXL97 from the given crystal dimensions. The ratio of minimum to maximum apparent transmission was determined experimentally as 0.742732.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.3670 (3)	0.1639 (3)	0.10021 (14)	0.0270 (4)
H1	0.438 (4)	0.018 (4)	0.108 (2)	0.034*
N2	0.3749 (3)	0.2670 (3)	−0.01267 (14)	0.0275 (4)
C3	0.2598 (3)	0.4796 (3)	0.00586 (17)	0.0256 (5)
O3	0.2342 (2)	0.6286 (2)	−0.08679 (12)	0.0306 (4)
H3	0.166 (4)	0.761 (4)	−0.059 (2)	0.038*
C4	0.1789 (3)	0.5110 (3)	0.12948 (16)	0.0249 (5)
N41	0.0462 (3)	0.7199 (3)	0.17586 (15)	0.0296 (4)
O41	−0.0311 (2)	0.7382 (2)	0.28295 (13)	0.0371 (4)
O42	0.0128 (3)	0.8841 (2)	0.10277 (14)	0.0413 (5)
C5	0.2535 (3)	0.2983 (3)	0.18861 (17)	0.0250 (5)
C51	0.2309 (3)	0.2081 (3)	0.31659 (17)	0.0287 (5)
C52	0.3656 (4)	−0.0443 (3)	0.32335 (19)	0.0351 (5)
H51	0.3038	−0.1120	0.2780	0.044*
H52	0.3500	−0.1018	0.4067	0.044*
H53	0.5294	−0.0807	0.2897	0.044*
C53	−0.0255 (3)	0.2613 (4)	0.36904 (19)	0.0356 (5)
H54	−0.1153	0.4220	0.3616	0.044*
H55	−0.0415	0.2093	0.4533	0.044*
H56	−0.0832	0.1863	0.3257	0.044*
C54	0.3329 (4)	0.3093 (4)	0.38784 (19)	0.0397 (6)
H57	0.4971	0.2696	0.3540	0.050*
H58	0.3166	0.2514	0.4711	0.050*
H59	0.2500	0.4712	0.3839	0.050*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0287 (9)	0.0183 (8)	0.0280 (9)	−0.0040 (6)	−0.0050 (7)	−0.0006 (6)
N2	0.0303 (9)	0.0207 (9)	0.0261 (9)	−0.0059 (7)	−0.0040 (7)	−0.0005 (6)
C3	0.0232 (9)	0.0219 (9)	0.0290 (10)	−0.0063 (7)	−0.0064 (7)	0.0001 (7)
O3	0.0339 (8)	0.0206 (7)	0.0317 (8)	−0.0057 (6)	−0.0078 (6)	0.0018 (6)
C4	0.0218 (9)	0.0194 (10)	0.0295 (10)	−0.0038 (7)	−0.0052 (7)	−0.0026 (7)
N41	0.0261 (8)	0.0223 (9)	0.0356 (10)	−0.0043 (6)	−0.0064 (7)	−0.0035 (7)
O41	0.0372 (8)	0.0310 (8)	0.0352 (9)	−0.0069 (6)	0.0012 (6)	−0.0118 (6)
O42	0.0488 (10)	0.0195 (7)	0.0431 (10)	−0.0025 (6)	−0.0081 (7)	−0.0007 (6)
C5	0.0206 (9)	0.0225 (9)	0.0296 (10)	−0.0053 (7)	−0.0051 (7)	−0.0038 (7)
C51	0.0252 (10)	0.0283 (10)	0.0283 (10)	−0.0073 (8)	−0.0049 (8)	0.0003 (8)
C52	0.0335 (11)	0.0306 (11)	0.0333 (11)	−0.0077 (9)	−0.0062 (9)	0.0043 (8)
C53	0.0302 (11)	0.0339 (11)	0.0354 (11)	−0.0095 (9)	−0.0001 (8)	−0.0006 (9)
C54	0.0398 (12)	0.0468 (13)	0.0339 (12)	−0.0156 (10)	−0.0116 (9)	−0.0039 (9)

Geometric parameters (Å, º) top

N1—C5	1.328 (3)	C51—C52	1.531 (3)
N1—N2	1.379 (2)	C51—C54	1.538 (3)
N1—H1	0.88 (3)	C51—C53	1.538 (3)
N2—C3	1.316 (2)	C52—H51	0.98
C3—O3	1.333 (2)	C52—H52	0.98
C3—C4	1.420 (3)	C52—H53	0.98
O3—H3	0.87 (3)	C53—H54	0.98
C4—N41	1.402 (2)	C53—H55	0.98
C4—C5	1.409 (3)	C53—H56	0.98
N41—O41	1.228 (2)	C54—H57	0.98
N41—O42	1.248 (2)	C54—H58	0.98
C5—C51	1.508 (3)	C54—H59	0.98

C5—N1—N2	115.54 (16)	C52—C51—C53	108.58 (16)
C5—N1—H1	126.1 (15)	C54—C51—C53	111.13 (17)
N2—N1—H1	118.4 (15)	C51—C52—H51	109.5
C3—N2—N1	103.85 (15)	C51—C52—H52	109.5
N2—C3—O3	119.47 (17)	H51—C52—H52	109.5
N2—C3—C4	110.65 (17)	C51—C52—H53	109.5
O3—C3—C4	129.88 (17)	H51—C52—H53	109.5
C3—O3—H3	107.6 (16)	H52—C52—H53	109.5
N41—C4—C5	129.88 (17)	C51—C53—H54	109.5
N41—C4—C3	123.47 (17)	C51—C53—H55	109.5
C5—C4—C3	106.64 (16)	H54—C53—H55	109.5
O41—N41—O42	122.35 (16)	C51—C53—H56	109.5
O41—N41—C4	121.21 (16)	H54—C53—H56	109.5
O42—N41—C4	116.44 (16)	H55—C53—H56	109.5
N1—C5—C4	103.32 (16)	C51—C54—H57	109.5
N1—C5—C51	121.22 (17)	C51—C54—H58	109.5
C4—C5—C51	135.46 (17)	H57—C54—H58	109.5
C5—C51—C52	109.91 (16)	C51—C54—H59	109.5
C5—C51—C54	109.69 (16)	H57—C54—H59	109.5
C52—C51—C54	108.19 (16)	H58—C54—H59	109.5
C5—C51—C53	109.32 (15)

C5—N1—N2—C3	0.2 (2)	N2—N1—C5—C51	179.91 (15)
N1—N2—C3—O3	−179.93 (15)	N41—C4—C5—N1	178.52 (17)
N1—N2—C3—C4	−0.2 (2)	C3—C4—C5—N1	−0.03 (19)
N2—C3—C4—N41	−178.50 (16)	N41—C4—C5—C51	−1.5 (3)
O3—C3—C4—N41	1.2 (3)	C3—C4—C5—C51	179.94 (19)
N2—C3—C4—C5	0.2 (2)	N1—C5—C51—C52	3.3 (2)
O3—C3—C4—C5	179.83 (18)	C4—C5—C51—C52	−176.7 (2)
C5—C4—N41—O41	−2.5 (3)	N1—C5—C51—C54	122.10 (19)
C3—C4—N41—O41	175.83 (17)	C4—C5—C51—C54	−57.9 (3)
C5—C4—N41—O42	177.17 (18)	N1—C5—C51—C53	−115.81 (19)
C3—C4—N41—O42	−4.5 (3)	C4—C5—C51—C53	64.2 (3)
N2—N1—C5—C4	−0.1 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···N2ⁱ	0.88 (3)	2.09 (3)	2.847 (2)	144 (2)
O3—H3···O42	0.87 (3)	2.02 (3)	2.718 (2)	136 (2)
O3—H3···O42ⁱⁱ	0.87 (3)	2.19 (3)	2.948 (2)	145 (2)

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

Acknowledgements

The authors thank the EPSRC National Crystallography Service (Southampton, England) and acknowledge the use of the EPSRC's Chemical Database Service at Daresbury Laboratory (Fletcher et al., 1996 ).

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