5-tert-But­yl-4-bromo-1,2-dihydro-1H-pyrazol-3(2H)-one monohydrate

Lynch, D.E.; McClenaghan, I.

doi:10.1107/S1600536805012791

organic compounds

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ISSN: 2056-9890

Volume 61| Part 8| August 2005| Pages o2349-o2351

https://doi.org/10.1107/S1600536805012791

5-tert-Butyl-4-bromo-1,2-dihydro-1H-pyrazol-3(2H)-one monohydrate

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 21 April 2005; accepted 22 April 2005; online 6 July 2005)

The structure of the title compound, C₇H₁₁BrN₂O·H₂O, exhibits an elaborate hydrogen-bonding network involving pyrazole N—H⋯O dimers and two other hydrogen-bonding motifs, both including water molecules. One motif is a distorted hexagonal R₃⁵(11) graph set, while the other is a distorted octagonal boat conformation R₆⁴(14) graph set.

Comment

In a series of studies on the preparation and hydrogen-bonding properties of 3,4,5-tri-substituted pyrazoles, we recently characterized the structure of 5-tert-butyl-4-nitro-1H-pyrazol-3-ol (Lynch & McClenaghan, 2005 ). We report here the structure of the title compound, (I). Similar to 5-tert-butyl-4-nitro-1H-pyrazol-3-ol, compound (I) originated from 3,5-di-tert-butylpyrazole. Compound (I) was prepared by reacting 3,5-di-tert-butylpyrazole with bromine in chloroform solution at room temperature. In these reactions, 3,5-di-t-butylpyrazole is attacked by either nitric acid (as in the case of 5-tert-butyl-4-nitro-1H-pyrazol-3-ol) or bromine to form the onium species, which then displaces one tert-butyl group. The subsequent vacant position is then filled by an OH group that, in the case of (I), tautomerizes to form the pyrazolone.

In the structure of (I) (Fig. 1), all strong hydrogen-bonding components are involved in the hydrogen-bonding network. The hydrogen-bonding geometry for this structure is listed in Table 1. The fourfold symmetry in (I) arises because of the unique hydrogen-bonded motif that is formed via contributions from eight pyrazole molecules and four water molecules. Each pyrazole molecule forms a centrosymmetric R₂²(8) graph set (Etter, 1990 ) dimer via N1—H⋯O5 interactions, at (x, y, z) and (−x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ), centred at ( $[{3\over 4}]$ , $[1\over 4]$ , $[1\over4]$ ). The N2/H group associates with O1W, at (x, y, z) and (y + $[{1\over 4}]$ , −x + $[{5\over 4}]$ , z + $[{1\over 4}]$ ). O1W, at (x, y, z), associates with two O5 atoms, one at (x, y, z) and the other at (−y + $[{5\over 4}]$ , x − $[{3\over 4}]$ , −z + $[{1\over 4}]$ ). Thus, each O5 atom is involved in a four-centre hydrogen-bonding association. For O5, at (x, y, z), the three non-H-atom contacts are O1W at (x, y, z), O1I at (y + $[{3\over 4}]$ , −x + $[{5\over 4}]$ , −z + $[{1\over 4}]$ ) and N1 at (−x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ) (Fig. 2). Three pyrazole molecules, at (x, y, z), (−x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ) and (−y + $[{5\over 4}]$ , x − $[{3\over 4}]$ , −z + $[{1\over 4}]$ ), and two water molecules, at (x, y, z) and (−y + $[{5\over 4}]$ , x − $[{3\over 4}]$ , −z + $[{1\over 4}]$ ), form a distorted hexagonal hydrogen-bonding motif [graph set R₃⁵(11)], adjoining the N1—H⋯O5 dimer, fused via the same interaction (Fig. 3). The hexagonal motifs are also fused with each other via the O1W—H⋯O5 interaction at (x, y, z). The resulting arrangement also creates a distorted octagonal boat conformation hydrogen-bonding motif [graph set R₆⁴(14)] involving four pyrazole groups, at (x, y, z), (−x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ), (x − $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ ) and (1 − x, −y + $[{1\over 2}]$ , z), and two water molecules, at (y + $[{1\over 4}]$ , −x + $[{5\over 4}]$ , z + $[{1\over 4}]$ ) and (−y + $[{3\over 4}]$ , x − $[{3\over 4}]$ , z + $[{1\over 4}]$ ) (Fig. 4). A stereoview of the unit cell contents of (I) is shown in Fig. 5. The Br atom does not contribute to the hydrogen-bonding network; atom Br4 is 3.469 (3) Å from O1W, and 3.412 (3) Å from N2(−y + $[{5\over 4}]$ , x − $[{1\over 4}]$ , z − $[{1\over 4}]$ ).

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

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

Figure 2
Hydrogen-bonding environment for (I)

, at (x, y, z), showing the centrosymmetric R₂²(8) N1—H⋯O5 dimer, the two hydrogen-bonding associations from O1W, and the four-centre hydrogen-bonding association involving O5. For clarity, H atoms not involved in the hydrogen-bonding interactions have been omitted. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) −x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (ii) y + $[{1\over 4}]$ , −x + $[{5\over 4}]$ , z + $[{1\over 4}]$ ; (iii) −y + $[{5\over 4}]$ , x − $[{3\over 4}]$ , −z + $[{1\over 4}]$ ; (iv) y + $[{3\over 4}]$ , −x + $[{5\over 4}]$ , −z + $[{1\over 4}]$ .]

Figure 3
Part of the structure of (I)

, at (x, y, z), showing the distorted R₃⁵(11) hexagonal motif, and its position with respect to the N1—H⋯O5 dimer. For clarity, H atoms not involved in the hydrogen-bonding interactions have been omitted. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) −x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (ii) −y + $[{5\over 4}]$ , x − $[{3\over 4}]$ , z − $[{1\over 4}]$ .]

Figure 4
Part of the structure of (I)

, at (x, y, z), showing the distorted R₆⁴(14) octagonal boat motif and its position with respect to the N1—H⋯O5 dimer. For clarity, H atoms not involved in the hydrogen-bonding interactions have been omitted. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (i) −x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ; (ii) −y + $[{3\over 4}]$ , x − $[{3\over 4}]$ , z + $[{1\over 4}]$ ; (iii) 1 − x, −y + $[{1\over 2}]$ , z; (iv) x − $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ ; (v) y + $[{1\over 4}]$ , −x + $[{5\over 4}]$ , z + $[{1\over 4}]$ .]

Figure 5
Stereoview of the unit cell contents of (I)

Experimental

The title compound was obtained from Key Organics Ltd, and crystals were grown from an ethanol solution.

Crystal data

C₇H₁₁BrN₂O·H₂O
M_r = 237.10
Tetragonal, I 4₁ /a
a = 13.6840 (4) Å
c = 21.4734 (8) Å
V = 4020.9 (2) Å³
Z = 16
D_x = 1.567 Mg m⁻³
Mo Kα radiation
Cell parameters from 2331 reflections
θ = 2.9–27.5°
μ = 4.06 mm⁻¹
T = 150 (2) K
Prism, colourless
0.36 × 0.27 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer
φ and ω scans
Absorption correction: multi-scan(SADABS; Sheldrick, 2003 )T_min = 0.288, T_max = 0.444
12 489 measured reflections
1977 independent reflections
1633 reflections with I > 2σ(I)
R_int = 0.069
θ_max = 26.0°
h = −16 → 16
k = −15 → 14
l = −19 → 26

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.069
S = 1.02
1977 reflections
124 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F_o²) + (0.0247P)² + 7.0406P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.64 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O5ⁱ	0.82 (3)	1.97 (3)	2.773 (3)	168 (3)
N2—H2⋯O1Wⁱⁱ	0.85 (3)	1.80 (3)	2.646 (3)	171 (3)
O1W—H1W⋯O5	0.83 (2)	1.91 (2)	2.733 (3)	169 (3)
O1W—H2W⋯O5ⁱⁱⁱ	0.83 (2)	1.91 (2)	2.739 (3)	173 (3)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, -y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) $[y+{\script{1\over 4}}, -x+{\script{5\over 4}}, z+{\script{1\over 4}}]$ ; (iii) $[-y+{\script{5\over 4}}, x-{\script{3\over 4}}, -z+{\script{1\over 4}}]$ .

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 NH H atoms involved in the hydrogen-bonding associations (Table 1) were located in Fourier syntheses and positional parameters were refined. The water H atoms were located and were refined with O—H distance restraints of 0.83 (2) Å and H⋯H restraints of 1.40 (2) Å. 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: PLATON97 (Spek, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536805012791/hg6180sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536805012791/hg6180Isup2.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: PLATON97 (Spek, 1997); software used to prepare material for publication: SHELXL97.

5-tert-Butyl-4-bromo-1,2-dihydro-1H-pyrazol-3(2H)-one monohydrate top

Crystal data top

C₇H₁₁BrN₂O·H₂O	D_x = 1.567 Mg m⁻³
M_r = 237.10	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4₁/a	Cell parameters from 2331 reflections
Hall symbol: -I 4ad	θ = 2.9–27.5°
a = 13.6840 (4) Å	µ = 4.06 mm⁻¹
c = 21.4734 (8) Å	T = 150 K
V = 4020.9 (2) Å³	Prism, colourless
Z = 16	0.36 × 0.27 × 0.20 mm
F(000) = 1920

Data collection top

Nonius KappaCCD? diffractometer	1977 independent reflections
Radiation source: Bruker-Nonius FR591 rotating anode	1633 reflections with I > 2σ(I)
10 cm confocal mirrors monochromator	R_int = 0.069
Detector resolution: 9.091 pixels mm^-1	θ_max = 26.0°, θ_min = 3.5°
φ and ω scans	h = −16→16
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	k = −15→14
T_min = 0.288, T_max = 0.444	l = −19→26
12489 measured reflections

Refinement top

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.069	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ²(F_o²) + (0.0247P)² + 7.0406P] where P = (F_o² + 2F_c²)/3
1977 reflections	(Δ/σ)_max < 0.001
124 parameters	Δρ_max = 0.30 e Å⁻³
3 restraints	Δρ_min = −0.64 e Å⁻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 0.630689.

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

	x	y	z	U_iso*/U_eq
Br4	0.688965 (19)	0.380502 (19)	0.044971 (12)	0.02124 (11)
O5	0.78480 (12)	0.27537 (13)	0.16996 (8)	0.0182 (4)
N1	0.64408 (16)	0.31605 (16)	0.22405 (10)	0.0166 (5)
H1	0.660 (2)	0.295 (2)	0.2582 (14)	0.021*
N2	0.55701 (16)	0.36121 (16)	0.21224 (10)	0.0170 (5)
H2	0.520 (2)	0.374 (2)	0.2427 (14)	0.021*
C3	0.55559 (18)	0.39126 (18)	0.15299 (12)	0.0157 (5)
C31	0.46896 (19)	0.44595 (19)	0.12557 (12)	0.0181 (6)
C32	0.5036 (2)	0.5478 (2)	0.10536 (15)	0.0265 (7)
H31	0.5258	0.5844	0.1419	0.033*
H32	0.4495	0.5829	0.0855	0.033*
H33	0.5577	0.5413	0.0757	0.033*
C33	0.4290 (2)	0.3888 (2)	0.06939 (13)	0.0262 (6)
H34	0.4803	0.3823	0.0378	0.033*
H35	0.3732	0.4239	0.0516	0.033*
H36	0.4080	0.3237	0.0829	0.033*
C34	0.3868 (2)	0.4572 (2)	0.17367 (14)	0.0267 (7)
H37	0.3655	0.3925	0.1877	0.033*
H38	0.3316	0.4917	0.1547	0.033*
H39	0.4109	0.4947	0.2094	0.033*
C4	0.64375 (18)	0.36354 (18)	0.12658 (11)	0.0151 (5)
C5	0.70015 (19)	0.31513 (18)	0.17256 (12)	0.0153 (5)
O1W	0.86437 (18)	0.19982 (16)	0.06359 (9)	0.0364 (6)
H1W	0.833 (2)	0.223 (2)	0.0934 (9)	0.045*
H2W	0.898 (2)	0.1507 (16)	0.0717 (13)	0.045*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br4	0.02379 (17)	0.02565 (17)	0.01427 (16)	0.00435 (11)	0.00409 (11)	0.00462 (11)
O5	0.0139 (9)	0.0236 (10)	0.0169 (10)	0.0034 (7)	−0.0003 (7)	0.0021 (8)
N1	0.0178 (12)	0.0201 (12)	0.0120 (11)	0.0017 (9)	−0.0013 (9)	0.0039 (9)
N2	0.0168 (12)	0.0194 (12)	0.0146 (12)	0.0018 (9)	0.0028 (9)	−0.0005 (9)
C3	0.0191 (14)	0.0131 (13)	0.0150 (13)	−0.0019 (10)	−0.0010 (10)	0.0017 (10)
C31	0.0180 (14)	0.0184 (13)	0.0180 (14)	0.0025 (10)	0.0006 (11)	0.0024 (11)
C32	0.0234 (15)	0.0232 (15)	0.0330 (17)	0.0022 (12)	0.0005 (13)	0.0043 (13)
C33	0.0251 (15)	0.0294 (16)	0.0241 (16)	0.0032 (13)	−0.0074 (13)	−0.0003 (13)
C34	0.0207 (15)	0.0312 (16)	0.0283 (17)	0.0069 (12)	0.0014 (13)	0.0048 (13)
C4	0.0181 (13)	0.0153 (13)	0.0117 (13)	0.0000 (10)	0.0013 (10)	0.0019 (10)
C5	0.0185 (14)	0.0120 (13)	0.0154 (14)	−0.0031 (10)	0.0000 (11)	−0.0012 (10)
O1W	0.0584 (16)	0.0321 (13)	0.0186 (11)	0.0256 (11)	0.0121 (10)	0.0073 (9)

Geometric parameters (Å, º) top

Br4—C4	1.873 (2)	C32—H31	0.98
O5—C5	1.281 (3)	C32—H32	0.98
N1—C5	1.346 (3)	C32—H33	0.98
N1—N2	1.366 (3)	C33—H34	0.98
N1—H1	0.82 (3)	C33—H35	0.98
N2—C3	1.337 (3)	C33—H36	0.98
N2—H2	0.85 (3)	C34—H37	0.98
C3—C4	1.386 (4)	C34—H38	0.98
C3—C31	1.521 (4)	C34—H39	0.98
C31—C34	1.534 (4)	C4—C5	1.417 (4)
C31—C32	1.535 (4)	O1W—H1W	0.83 (2)
C31—C33	1.538 (4)	O1W—H2W	0.83 (2)

C5—N1—N2	110.4 (2)	H32—C32—H33	109.5
C5—N1—H1	125 (2)	C31—C33—H34	109.5
N2—N1—H1	124 (2)	C31—C33—H35	109.5
C3—N2—N1	109.2 (2)	H34—C33—H35	109.5
C3—N2—H2	131 (2)	C31—C33—H36	109.5
N1—N2—H2	119 (2)	H34—C33—H36	109.5
N2—C3—C4	107.0 (2)	H35—C33—H36	109.5
N2—C3—C31	122.1 (2)	C31—C34—H37	109.5
C4—C3—C31	130.9 (2)	C31—C34—H38	109.5
C3—C31—C34	111.1 (2)	H37—C34—H38	109.5
C3—C31—C32	108.4 (2)	C31—C34—H39	109.5
C34—C31—C32	109.0 (2)	H37—C34—H39	109.5
C3—C31—C33	109.3 (2)	H38—C34—H39	109.5
C34—C31—C33	108.6 (2)	C3—C4—C5	108.5 (2)
C32—C31—C33	110.5 (2)	C3—C4—Br4	129.53 (19)
C31—C32—H31	109.5	C5—C4—Br4	121.99 (19)
C31—C32—H32	109.5	O5—C5—N1	123.7 (2)
H31—C32—H32	109.5	O5—C5—C4	131.3 (2)
C31—C32—H33	109.5	N1—C5—C4	104.9 (2)
H31—C32—H33	109.5	H1W—O1W—H2W	116 (3)

C5—N1—N2—C3	−0.6 (3)	C31—C3—C4—C5	179.2 (3)
N1—N2—C3—C4	0.5 (3)	N2—C3—C4—Br4	178.78 (19)
N1—N2—C3—C31	−178.9 (2)	C31—C3—C4—Br4	−1.8 (4)
N2—C3—C31—C34	−1.8 (4)	N2—N1—C5—O5	−178.3 (2)
C4—C3—C31—C34	178.8 (3)	N2—N1—C5—C4	0.4 (3)
N2—C3—C31—C32	117.9 (3)	C3—C4—C5—O5	178.5 (3)
C4—C3—C31—C32	−61.5 (4)	Br4—C4—C5—O5	−0.6 (4)
N2—C3—C31—C33	−121.6 (3)	C3—C4—C5—N1	−0.1 (3)
C4—C3—C31—C33	59.0 (4)	Br4—C4—C5—N1	−179.23 (17)
N2—C3—C4—C5	−0.3 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O5ⁱ	0.82 (3)	1.97 (3)	2.773 (3)	168 (3)
N2—H2···O1Wⁱⁱ	0.85 (3)	1.80 (3)	2.646 (3)	171 (3)
O1W—H1W···O5	0.83 (2)	1.91 (2)	2.733 (3)	169 (3)
O1W—H2W···O5ⁱⁱⁱ	0.83 (2)	1.91 (2)	2.739 (3)	173 (3)

Symmetry codes: (i) −x+3/2, −y+1/2, −z+1/2; (ii) y+1/4, −x+5/4, z+1/4; (iii) −y+5/4, x−3/4, −z+1/4.

Acknowledgements

The authors thank the EPSRC National Crystallography Service (Southampton, England).

References

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